literature review discussion template

Systematic Review Discussion Example

Automate every stage of your literature review to produce evidence-based research faster and more accurately.

What should be included in the discussion section of a systematic review.

There are a number of key elements that are included in a discussion section of a systematic review. Remember to use all these elements to ensure the quality of your review remains high, that your review is deemed useful to your peers, and that the validity of your systematic review cannot be questioned.

The first thing to do in your discussion is to summarize your most important findings. This can simply be identifying your key results. Be careful not to just repeat all the results you have outlined in your previous sections. Instead, once you have briefly mentioned them, go on to interpret them. The results from included studies are presented in a summary. The results are then compared among different studies, and the consistent themes, agreements, and contradictions among studies are identified. The consistencies are reported and reasons for contradictions are given. The themes and agreement among the studies are used to answer the research question. Your interpretations need to be backed up by evidence so that they make the intended impact. Interpretations can be based on your critical thinking. Your interpretations of study findings can be compared to the interpretation of another review on the same topic.

Another way to ensure that your review is as persuasive as possible is to discuss any strengths and weaknesses at this point, in your discussion. It is advisable to first talk about the most notable strengths and limitations of included studies. Afterward, you can show how the characteristics of individual included studies have affected the strengths and limitations of the review. Identifying weaknesses may not be immediately obvious for some writers of reviews. However, they are essential to include, especially in the discussion section, as it means you can explain them and examine why your findings are still valid, despite such weaknesses. Discussing strengths will support your view even further. By highlighting both strengths and weaknesses together, you can dismiss any negative criticism before it even begins.

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How Long Should A Discussion Be In A Systematic Review?

When it comes to the length of a discussion section, there is never really a right or wrong answer. The length of the discussion section is a systematic review is usually determined by the number of included studies, the scope of the research question, and the ability of the author to analyze and synthesize data from the included studies. That being said, given the breadth and number of areas to be covered as mentioned above, it will never be just one paragraph. Examining the strengths and weaknesses of your review alone will often call for a couple of paragraphs of discussion. Then you assert your findings that will answer your research question and support your initial hypothesis. This will likely demand another paragraph or two at least.

The Importance of Systematic Review Discussion

Remember that the discussion section of your review is, arguably, the most important part of your work. It is where you can put your label on all previous studies conducted, and highlight why your research into the area has been a worthwhile process. It is an opportunity for you to set yourself apart, and have your paper be seen as evidence for the subject matter in question. Therefore, the importance of a systematic review discussion cannot be overstated. The discussion section of a review is your chance to present the results of your analysis, which takes into account all previous studies or research in the area.

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• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

Prevent plagiarism, run a free check.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

Cite this Scribbr article

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• CAREER FEATURE
• 04 December 2020
• Correction 09 December 2020

How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

You can also search for this author in PubMed   Google Scholar

Literature reviews are important resources for scientists. They provide historical context for a field while offering opinions on its future trajectory. Creating them can provide inspiration for one’s own research, as well as some practice in writing. But few scientists are trained in how to write a review — or in what constitutes an excellent one. Even picking the appropriate software to use can be an involved decision (see ‘Tools and techniques’). So Nature asked editors and working scientists with well-cited reviews for their tips.

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doi: https://doi.org/10.1038/d41586-020-03422-x

Interviews have been edited for length and clarity.

Updates & Corrections

Correction 09 December 2020 : An earlier version of the tables in this article included some incorrect details about the programs Zotero, Endnote and Manubot. These have now been corrected.

Hsing, I.-M., Xu, Y. & Zhao, W. Electroanalysis 19 , 755–768 (2007).

Article   Google Scholar  

Ledesma, H. A. et al. Nature Nanotechnol. 14 , 645–657 (2019).

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Brahlek, M., Koirala, N., Bansal, N. & Oh, S. Solid State Commun. 215–216 , 54–62 (2015).

Choi, Y. & Lee, S. Y. Nature Rev. Chem . https://doi.org/10.1038/s41570-020-00221-w (2020).

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

Literature Review Tips for the Introduction and Discussion Sections

A literature review is a summary of studies related to a particular area of research. It identifies and summarizes all the relevant research conducted on a particular topic. It is important that your literature review is focused . Therefore, you should choose a limited number of studies that are central to your topic rather than trying to collect a wide range of studies that might not be closely connected.

Literature reviews help you accomplish the following:

• Evaluate past research  Collecting relevant resources will help you see what research has already been done. This will also help avoid duplication.
• Identify experts It is important to identify credible researchers who have knowledge in a given field, in order to seek their help if you get stuck with certain aspects of your research.
• Identify key questions  Your ultimate aim is to bring something new to the conversation. Collecting resources will help you determine the important questions that need to be addressed.
• Determine methodologies used in past studies Knowing how others have approached a particular topic will give you the opportunity to identify problems and find new ways to research and study a topic. If the reported methodology was successful, you can use it and save time that you would otherwise be spending on optimization.

Presenting Literature Review in the Introduction and Discussion Sections

There are many benefits to presenting literature reviews in the introduction and discussion sections of your manuscripts . However, there are differences in how you can present literature reviews in each section.

What Should be Included in the Literature Review of the Introduction Section?

The literature reviewed in the introduction should:

• Introduce the topic
• Establish the significance of the study
• Provide an overview of the relevant literature
• Establish a context for the study using the literature
• Identify knowledge gaps
• Illustrate how the study will advance knowledge on the topic

As you can see, literature review plays a significant role in the introduction section. However, there are some things that you should avoid doing in this section. These include:

• Elaborating on the studies mentioned in the literature review
• Using studies from the literature review to aggressively support your research
• Directly quoting studies from the literature review

It is important to know how to integrate the literature review into the introduction in an effective way. Although you can mention other studies, they should not be the focus. Instead, focus on using the literature review to aid in setting a foundation for the manuscript.

What Goes in the Literature Review of the Discussion Section?

Literature reviews play an important role in the discussion section of a manuscript . In this section, your findings should be the focus, rather than those of other researchers. Therefore, you should only use the studies mentioned in the literature review as support and evidence for your study.

There are three ways in which you can use literature reviews in the discussion section:

• To Provide Context for Your Study Using studies from the literature review helps to set the foundation for how you will reveal your findings and develop your ideas.
• Compare your Findings to Other Studies You can use previous literature as a backdrop to compare your new findings. This helps describe and also advance your ideas.
• State the Contribution of Your Study In addition to developing your ideas, you can use literature reviews to explain how your study contributes to the field of study.

However, there are three common mistakes that researchers make when including literature reviews in the discussion section. First, they mention all sorts of studies, some of which are not even relevant to the topic under investigation. Second, instead of citing the original article, they cite a related article that mentions the original article. Lastly, some authors cite previous work solely based on the abstract, without even going through the entire paper.

We hope this article helps you effectively present your literature review in both the introduction as well as the discussion section of your manuscript. You can also mention any other tips that will add to this article in the comments section below.

References:

[1]  http://www.math.montana.edu/jobo/phdprep/documents/phd6.pdf 

[2]  https://libguides.unf.edu/c.php?g=177129&p=1163732

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What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 

How to write a good literature review 

• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• How to write a literature review faster with Paperpal? 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

1. Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 

2. Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 

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3. Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 

4. Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 

5. Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 

6. Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

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Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

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Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

Whether you’re exploring a new research field or finding new angles to develop an existing topic, sifting through hundreds of papers can take more time than you have to spare. But what if you could find science-backed insights with verified citations in seconds? That’s the power of Paperpal’s new Research feature!  

How to write a literature review faster with Paperpal?

Paperpal, an AI writing assistant, integrates powerful academic search capabilities within its writing platform. With the Research feature, you get 100% factual insights, with citations backed by 250M+ verified research articles, directly within your writing interface with the option to save relevant references in your Citation Library. By eliminating the need to switch tabs to find answers to all your research questions, Paperpal saves time and helps you stay focused on your writing.   

Here’s how to use the Research feature:  

• Ask a question: Get started with a new document on paperpal.com. Click on the “Research” feature and type your question in plain English. Paperpal will scour over 250 million research articles, including conference papers and preprints, to provide you with accurate insights and citations. 
• Review and Save: Paperpal summarizes the information, while citing sources and listing relevant reads. You can quickly scan the results to identify relevant references and save these directly to your built-in citations library for later access. 
• Cite with Confidence: Paperpal makes it easy to incorporate relevant citations and references into your writing, ensuring your arguments are well-supported by credible sources. This translates to a polished, well-researched literature review. 

The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a good literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. By combining effortless research with an easy citation process, Paperpal Research streamlines the literature review process and empowers you to write faster and with more confidence. Try Paperpal Research now and see for yourself.  

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

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Get Organized

• Lit Review Prep Use this template to help you evaluate your sources, create article summaries for an annotated bibliography, and a synthesis matrix for your lit review outline.

Synthesize your Information

Synthesize: combine separate elements to form a whole.

Synthesis Matrix

A synthesis matrix helps you record the main points of each source and document how sources relate to each other.

After summarizing and evaluating your sources, arrange them in a matrix or use a citation manager to help you see how they relate to each other and apply to each of your themes or variables.  

By arranging your sources by theme or variable, you can see how your sources relate to each other, and can start thinking about how you weave them together to create a narrative.

• Step-by-Step Approach
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Evidence-Based Practice (EBP)

• The EBP Process
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• Writing a Literature Review
• Finding Psychological Tests & Assessment Instruments

What Is a Literature Review?

A literature review is an integrated analysis of scholarly writings that are related directly to your research question. Put simply, it's  a critical evaluation of what's already been written on a particular topic . It represents the literature that provides background information on your topic and shows a connection between those writings and your research question.

A literature review may be a stand-alone work or the introduction to a larger research paper, depending on the assignment. Rely heavily on the guidelines your instructor has given you.

What a Literature Review Is Not:

• A list or summary of sources
• An annotated bibliography
• A grouping of broad, unrelated sources
• A compilation of everything that has been written on a particular topic
• Literary criticism (think English) or a book review

Why Literature Reviews Are Important

• They explain the background of research on a topic
• They demonstrate why a topic is significant to a subject area
• They discover relationships between research studies/ideas
• They identify major themes, concepts, and researchers on a topic
• They identify critical gaps and points of disagreement
• They discuss further research questions that logically come out of the previous studies

To Learn More about Conducting and Writing a Lit Review . . .

Monash University (in Australia) has created several extremely helpful, interactive tutorials. 

• The Stand-Alone Literature Review, https://www.monash.edu/rlo/assignment-samples/science/stand-alone-literature-review
• Researching for Your Literature Review,  https://guides.lib.monash.edu/researching-for-your-literature-review/home
• Writing a Literature Review,  https://www.monash.edu/rlo/graduate-research-writing/write-the-thesis/writing-a-literature-review

Keep Track of Your Sources!

A citation manager can be helpful way to work with large numbers of citations. See UMSL Libraries' Citing Sources guide for more information. Personally, I highly recommend Zotero —it's free, easy to use, and versatile. If you need help getting started with Zotero or one of the other citation managers, please contact a librarian.

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• URL: https://libguides.umsl.edu/ebp

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A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

• Give a new interpretation of old material or combine new with old interpretations,
• Trace the intellectual progression of the field, including major debates,
• Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
• Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

• Place each work in the context of its contribution to understanding the research problem being studied.
• Describe the relationship of each work to the others under consideration.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.
• Resolve conflicts amongst seemingly contradictory previous studies.
• Identify areas of prior scholarship to prevent duplication of effort.
• Point the way in fulfilling a need for additional research.
• Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE: Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

• An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
• Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
• An explanation of how each work is similar to and how it varies from the others,
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

• Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
• Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
• Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness -- which of the author's theses are most convincing or least convincing?
• Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

• Current Situation : Information necessary to understand the current topic or focus of the literature review.
• Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
• History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
• Standards : Description of the way in which you present your information.
• Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

• Sources in your literature review do not clearly relate to the research problem;
• You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
• Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
• Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
• Does not describe the search procedures that were used in identifying the literature to review;
• Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
• Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

• How are they organizing their ideas?
• What methods have they used to study the problem?
• What theories have been used to explain, predict, or understand their research problem?
• What sources have they cited to support their conclusions?
• How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

• Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
• Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
• Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

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What is a literature review? [with examples]

What is a literature review?

The purpose of a literature review, how to write a literature review, the format of a literature review, general formatting rules, the length of a literature review, literature review examples, frequently asked questions about literature reviews, related articles.

A literature review is an assessment of the sources in a chosen topic of research.

In a literature review, you’re expected to report on the existing scholarly conversation, without adding new contributions.

If you are currently writing one, you've come to the right place. In the following paragraphs, we will explain:

• the objective of a literature review
• how to write a literature review
• the basic format of a literature review

Tip: It’s not always mandatory to add a literature review in a paper. Theses and dissertations often include them, whereas research papers may not. Make sure to consult with your instructor for exact requirements.

The four main objectives of a literature review are:

• Studying the references of your research area
• Summarizing the main arguments
• Identifying current gaps, stances, and issues
• Presenting all of the above in a text

Ultimately, the main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

The format of a literature review is fairly standard. It includes an:

• introduction that briefly introduces the main topic
• body that includes the main discussion of the key arguments
• conclusion that highlights the gaps and issues of the literature

➡️ Take a look at our guide on how to write a literature review to learn more about how to structure a literature review.

First of all, a literature review should have its own labeled section. You should indicate clearly in the table of contents where the literature can be found, and you should label this section as “Literature Review.”

➡️ For more information on writing a thesis, visit our guide on how to structure a thesis .

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, it will be long. If your paper does not depend entirely on references, it will be short.

Take a look at these three theses featuring great literature reviews:

• School-Based Speech-Language Pathologist's Perceptions of Sensory Food Aversions in Children [ PDF , see page 20]
• Who's Writing What We Read: Authorship in Criminological Research [ PDF , see page 4]
• A Phenomenological Study of the Lived Experience of Online Instructors of Theological Reflection at Christian Institutions Accredited by the Association of Theological Schools [ PDF , see page 56]

Literature reviews are most commonly found in theses and dissertations. However, you find them in research papers as well.

There is no set amount of words for a literature review, so the length depends on the research. If you are working with a large amount of sources, then it will be long. If your paper does not depend entirely on references, then it will be short.

No. A literature review should have its own independent section. You should indicate clearly in the table of contents where the literature review can be found, and label this section as “Literature Review.”

The main goal of a literature review is to provide the researcher with sufficient knowledge about the topic in question so that they can eventually make an intervention.

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What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

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1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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How to Write a Literature Review for Research: Guide, Structure & Template Examples

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A literature review is a critical analysis of published research on a particular topic. It involves reviewing and analyzing a range of sources, such as academic articles, books, and reports. Students conduct a literature review before writing a research paper or dissertation to gain an understanding of the existing knowledge and recognize areas for further exploration.

Evaluating scholarly works is a crucial aspect of academic work because it establishes the foundation for an inquiry and uncovers new information or gaps in studies. Thus, it is essential to develop and structure it correctly.  In this guide you will find:

• A detailed definition
• Elements of a good literary review
• How to do a literature review
• Examples of literature review template.

Read on to explore the structure and straightforward steps for assessing existing sources on your topic.  In case you are looking for a quick solution, consider giving our literature review services a try. 

What Is a Literature Review: Definition

Before delving further, let’s first define what is a literature review in research. As a researcher, you might need to objectively synthesize, explore, and evaluate existing studies conducted by others. A literature review helps you identify gaps or areas that require further investigation. It boils down to analyzing and making sense of a massive body of knowledge. It is crucial to be critical during the entire process as it is the most effective approach to engaging with texts. You need to objectively identify their strengths and weaknesses, and convey your positive or negative views.   In other words, literature reviews are about deducing specific sources and comparing relevant studies to find similarities and differences. This process may reveal new perspectives or offer a thorough outline for further developments in a specific field. It can also inform readers about the relevance and validity of existing documents to the statement of the problem . You conduct a lit review to get an overview of concepts surrounding your subject, keep up to date with trends in your field, and enhance your credibility. Besides, it offers a solid background for a research paper , thesis or dissertation .

What Is the Purpose of a Literature Review?

A literature review must highlight your overall knowledge of a research subject and help you develop an argument, mostly by responding to a specific question. It is not just a summary of what you have read.  Commonly, the purpose of a literature review is to help you:

• Understand and convey the current state of literature on your research topic .
• Find adequate documents on your subject to form your perspective.
• Create a framework for your paper based on research goals.
• Identify gaps in studies and develop novel research questions .
• Select appropriate methods by locating tried and tested techniques.

Note that keeping all these points in mind is important to get the most from an evaluation process when conducting the review.

Types of Literature Reviews

There are various types of literature reviews, each with specific expectations in terms of depth, structure, length, and scope. Here are the main ones:

• Stand-alone literature review. This type involves a comprehensive analysis of prior research related to a specific question. Here, your task is to evaluate and compare existing studies, identify trends, and recognize gaps, weaknesses, and controversies in the field.
• Literature review for a journal article. In this case, the analysis of literature focuses on providing background information for an inquiry being conducted. It is usually placed in an introduction or combined with the discussion of results.
• Literature review assignment. Students may be assigned a selective project to familiarize themselves with a theme and studies in their field. The intention could also be to identify gaps in the current knowledge base to suggest new questions, develop a theoretical framework in research , or determine a suitable methodology for future exploration. This type deals with a small part of research on a subject and stands as a complete work.
• Research paper literature review. The main objective here is to facilitate scholars in gathering, condensing, synthesizing, and examining current research on a specific issue. This is particularly beneficial to academics who are investigating a new area of study or seeking guidance on topics that have not yet been thoroughly explored.
• Thesis or dissertation literature review. This is a separate chapter placed after the Ph.D. thesis introduction and before the dissertation methodology section. It helps the author understand what has already been studied and what gaps exist in the current knowledge. By analyzing the existing research, a researcher can identify opportunities for further investigation and ensure that their study is original and significant.

How Long Should a Literature Review Be?

If the instructions for a task do not specify the required length of the literature review, there are some guidelines to consider. In general, it would be enough to have 20-25% of the total size of your work as an analysis part. Typically, the analysis section of the review should constitute around 20-25% of the total length of the work. However, several factors, such as the project purpose, intended audience, type, and scope, may affect how long a literature review is. For example, a dissertation usually requires an extensive literature evaluation section. The best assessments, however, are usually not less than 2 pages long.  If you are uncertain about the appropriate length, refer to the table below for guidance. Literature Review Length in Different Projects

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Features of a Good Literature Review

Regardless of your work’s nature, composing a good literature review is a laborious process that many students rightfully find challenging. This is because you may need to go through numerous studies and identify gaps, recognize frameworks, cite sources, and ensure coherence. Therefore, to develop a decent piece it is essential to consider the characteristics described below. The best work:

• Is more than just a list of relevant studies: you should critically examine others’ ideas and assess how they are presented.
• Considers a variety of reliable and applicable sources: a scientific literature review should demonstrate that you are familiar with relevant readings on your topic. Thus, ensure you have covered important, broad, latest, and pertinent texts. Such an approach enhances the depth of your evaluation and highlights various viewpoints.
• Demonstrates an awareness of values and theories underpinning the work: in the first place, you must understand why exactly you are conducting the evaluation. If you don’t know the purpose and function of the process, you will not write effectively.
• Relates papers to each other by comparing and contrasting them: a literature review in research moves past simple descriptions of what others have written. Rather, it entails connecting, finding differences and similarities, and interpreting concepts.
• Offers personal reactions and opinions to manuscripts: after comparing, contrasting, and critiquing others’ works, you should present your own interpretation and analysis.
• Showcases research gaps that your study will deal with and help address.
• Applies appropriate linking/transition words such as “similarly”, “however”, “also”, “contend”, “conclude”, “argue”, and “assert”: this helps you group together related notions, highlight contrasting views, and introduce others’ opinions or texts while remaining objective throughout the analysis.

What to Include in a Literature Review?

At this point, you understand the definitions, purpose, and features of a literature review. Now you need to present information effectively. Like in any other formal paper, your work must have a basic structure comprising an introduction, body, and conclusion.  But what does it look like? The layout goes beyond these sections because you must also consider how your themes and arguments will be organized.  Here is a detailed description of the three main parts of a literature review:

• Introduction Your first section should be brief, direct, and focused. Explain the main themes or topics to be analyzed, the arguments you will present, and the underlying reasons for your claims.
• Body In this section, conduct a comprehensive evaluation of the selected sources and organize them using a specific approach, such as themes or topics. Make sure to present your arguments clearly, linking them to studies that support or contradict your assessment. Remember to include viewpoints that disagree with your position to strengthen your evaluation. Cite the works of various authors you are critically analyzing, and limit the use of direct quotes. Instead, paraphrase and include references.
• Conclusion Summarize your literature review by highlighting the conclusions drawn from your analysis. You can restate gaps in knowledge, explain how your study will address them, and recommend future research needed on the topic.

Look at the example of the literature review template below to learn more.

Read more: Literature Review Outline

How to Structure a Literature Review?

Once you are ready to begin writing a literature review, it is necessary to think about how you will organize information. This helps avoid the risk of your work turning into a loose sequence of summaries instead of a logical and integrated analysis.  A literature review structure should be chosen based on the style used in your body section. Here are the major approaches you can use:

• Thematic This approach involves organizing your analysis around themes, topics, or issues. It is particularly useful when focusing on a single overarching subject and enables you to highlight critical debates within sub-themes.
• Chronological Literature reviews using this format organize studies based on when they were published, typically moving from older to newer works to explore the topic's development over time. It is important to analyze sources by considering any debates and turning points that influenced the subject and offer your interpretation.
• Methodological This design focuses on the methods other researchers used. A review of literature using this layout considers the perspective from which a particular theme was examined or the procedures used to answer a specific question. It may use qualitative, quantitative, or other strategies within these two broad techniques.
• Theoretical A theoretical approach involves a systematic and critical examination of existing theories, models, and frameworks related to the research topic or question. This approach helps to establish the context, identify gaps, and provide a foundation for your own research.

How to Write a Literature Review?

If you are still wondering how to write a literature review for a research paper, thesis or dissertation, this guideline will help you get started. While you have learned about important elements such as structuring and organization, you may still need guidance on how to establish your foundation for creating your review.  The following sections provide easy-to-understand explanations on how to write a lit review. Below are 7 steps you must follow to develop a decent paper.

1. Select a Topic and Narrow It Down

As you begin reviewing literature, it is vital to get your focus correct. Depending on your field of study, the selected topic must be:

• Relevant and important Explore a crucial concern in your field so that people will be interested in your work and you will have sufficient material to base your project on.
• Interesting This is essential because learning how to write a good literature review starts with being inquisitive since you can’t investigate something that doesn’t arouse your curiosity.
• Well defined this helps you include only relevant publications to make your paper helpful.
• Narrow Your theme must be specific yet researched enough to allow for an in-depth analysis. Broad issues usually necessitate a large number of studies, which will be impossible to explore meaningfully.

2. Search for Pertinent Literature

After having selected a topic for your research literature review, you need to search for studies. As you do this research, you'll want to take note of the keywords and phrases that appear frequently in the articles. These keywords can be used to create a list of search terms that you'll use to find additional articles on your topic. To ensure that your search terms are effective, you should try to identify the most important keywords and phrases related to your topic. These might be the names of key researchers, conceptual frameworks , theories, or techniques related to your topic. Consider the headings that the documents have been tagged with and words occurring in abstracts and titles. You can then organize your phrases into blocks based on the main ideas. Once you have identified the relevant keywords for your scientific literature review, it's time to search for articles. To do this, you'll need to choose at least two credible databases to search for good articles. Popular options include:

• Google Scholar

But there may be other databases that are more appropriate for your specific topic. When searching across different databases, it's important to use a uniform search strategy. This means combining your search terms using " OR " and " AND " to create a block of related terms. You can then type this block into the basic search box or use the advanced search feature, enclosing the terms in parentheses. This makes it easier to find specific articles. For example, consider these keywords:

Crohn’s disease, ulcerative colitis, adolescents, young adults, and management. The search term block would be “(Crohn’s disease OR ulcerative colitis) AND (young adults OR adolescent) AND management”.

Since the generated results may contain irrelevant or unreliable sources, ensure that you select only dependable ones. This is a key skill to develop when conducting a literature review because it allows you to choose the best articles to support your arguments.

3. Analyze and Choose Relevant Sources

After completing your search for articles and selecting databases, it's time to review the sources and choose which ones to include in your lit review. Focus on studies that are relevant to your topic and meet any other inclusion criteria.  To determine whether an article is relevant to your project, you'll need to read it carefully and grasp the arguments presented. Take notes as you read, recording interesting facts, main points, and any thoughts you have about the article. This will help you remember which author made which arguments, your impressions of the article, and any relationships you identified between different sources. As you read, try to answer these questions:

• What is the main argument of the article?
• How does the author support their argument?
• What is the research question or objective of the study?
• What research methods were used, and were they appropriate for the research question?
• What were the main findings or results of the study?
• Were the results statistically significant, and were the conclusions supported by the data?
• Are there any limitations or weaknesses to the study that should be considered?
• Are the authors qualified to conduct this research?
• Are there any conflicts of interest or biases that may affect the study's findings?
• Is the article well-written and easy to understand?
• Are the sources cited in the article reliable and relevant to the topic?

Remember that you can only start to write your literature review after going through all your manuscripts. Therefore, creating a rough draft is essential as this gives you a general idea of the volume of available material available. While conducting a literature review, you must examine the quality of all sources critically. This typically entails using a checklist or table to evaluate aspects such as methods, results, and presentation. An example of a template to assess sources for a literature review is provided below. It contains questions and criteria that assist in locating bias, errors, or flaws. Template for Literature Evaluation

4. Group the Sources by Categories

To write a review of literature, you need to sort your sources. After reading and evaluating your articles, you should have a general idea of the main achievements, major debates, themes, trends, and outstanding issues/questions. The next step is to organize your sources into logical categories. Good research literature reviews are systematic and consistent. You may choose to arrange your sources by topic, research methodology , geographic location, or other relevant criteria. It's also helpful to use subheadings within each category to further organize your sources. As you group your sources, be sure to consider how they relate to one another and to the overall research question or topic. You may find that certain sources address multiple themes or issues. In this case you'll need to decide which category is the most appropriate for each source. Remember that the purpose of organizing your sources is to provide a clear and coherent structure for your literature review. By grouping your sources into logical categories, you make it easier for your readers to follow your arguments and understand the connections between different sources. Here is an example of how to group sources by categories.

5. Build Connection Between Your Ideas and the Literature

To complete this step of the literature review, you need to connect your research, arguments, or ideas to the texts you've gathered. Begin by using your research question to identify connections between your sources and insights into your findings. Match your key concepts with the central points in each article to establish associations between topics. Be aware that you may see differences or contradictions between readings. To ensure that you're ready to write your literature review, use your key concepts as headings in your notes to easily locate articles that address specific themes. Observe and make explicit the relationships that emerge between your arguments and the manuscripts. These connections will be useful when structuring your work and selecting the papers to include in your project.

6. Write a Literature Review

At this point, you can start a literature review because you have already synthesized relevant works in your mind and recorded the details. With that information in mind, it is time to begin composing the actual analysis and thoroughly creating each of the components of a literature review.  Initiate the process by highlighting your topic and your overall argument or view.  Just like any other academic essay , your project must be well-structured and contain an introduction, main part, and conclusion. Consider the following explanations on how to write a literature review for a dissertation, thesis, or research paper.

Literature Review Introduction

The introduction section should provide the necessary background information and clarify the purpose of your analysis.  Begin by broadly announcing the topic and providing contextual details of major concepts and terms, such as what is already known about the subject and how the field has developed. Next, provide specific and relevant information about the issue and explain why it is important or why readers should engage with your work. Finally, describe the organization, scope, and aim or highlight the key points that will be discussed. Look at the following example to see how you can write an introduction for a literature review. Literature Review Introduction Example

The concentration of carbon emissions has been increasing throughout the years. The amount was 290 ppm before the industrial revolution but rose to 450 ppm afterward (Block, 2019, Wbeltz, 2020). These changes will affect the global climate significantly by influencing mean temperatures and precipitation levels. In turn, this will put pressure on global agricultural production and affect the growth speed, crop quality, and yield of staple foods like wheat (Wbeltz, 2020). Since over 90% of people worldwide depend on this crop, it must survive any climate changes. Thus, the purpose of this review is to evaluate how carbon emissions will affect global wheat production and identify any mitigation measures. The paper will explore wheat growth, yield, and quality in the face of elevated carbon levels.

Lit Review Body

The body section of your literature review is where you analyze relevant studies related to your topic. It is essential to organize your analysis coherently and logically.  Identify important sub-topics and structuring them to support your arguments. Using subheadings under major themes can help to order and focus your work effectively.  While writing the body of your literature review, you should critically examine texts.  This involves recognizing gaps, points of agreement or disagreement, and key subjects.  You can structure this section chronologically, thematically, theoretically, or methodologically, depending on your research question and the nature of your sources. Remember to use reliable and accurate references to support your arguments. Consider this example: Example of a Literature Review Paper Body Section

Various studies show that elevated carbon emissions result in increased crop growth. Adams (2018) attributes this to improved photosynthesis in leaves when exposed to high carbon levels in the air. Other studies argue that carbon enriches crops, accelerates and amplifies their productivity, and causes improved growth (Hog, 2020). In an experimental study, Li (2019) compared crop growth under high carbon conditions and found that a 500 ppm level enhances growth by nearly 8%. Nevertheless, high carbon levels also result in other effects such as high temperatures (Daley, 2019). In turn, this leads to short growth periods or cycles. Thus, an increase in temperature while accelerating the time for growth adversely affects crop quality (Adams, 2020).

Literature Review Conclusion

The concluding section of a literature review should show how you addressed the topic or achieved your purpose. You should then mention the major arguments you examined before identifying their implications in the broader field. Remember to recommend any applicable future research. Also, keep in mind these things when writing your literature review conclusion:

• Avoid in-text citations.
• Do not include new information.
• Highlight main ideas raised in the body paragraphs.
• Give your general view of the studies and explain your conclusions and underlying reasons.

Here is a sample literature review conclusion. Literature Review Conclusion Example

The review aimed to explore the effect of elevated carbon levels on global wheat production. Assessments of effects on the crop’s growth, yield, and quality were conducted to understand how changes in climate due to increasing carbon emissions will affect global agriculture. Findings demonstrate a definite impact of these changes on the aforementioned aspects. In particular, elevated carbon levels lead to enhanced growth, shorter growth cycle, and low and poor quality yields. It is suggested that future studies should further explore the role of other factors such as soil health and fertilizer use in explaining these effects because modern agricultural techniques are considered to harm soil quality.

7. Proofread and Revise Your Review of Literature

Once you are done with reviewing your literature, give yourself some time off and then come back to edit it. Attend to its narrative and flow by ensuring that all parts fit together and transition smoothly from one paragraph to another. Improve any poor connections, revise to enhance clarity, or re-write sentences to eradicate construction mistakes. You can then give your scientific literature review to a colleague or friend, who is not an expert in the field, and ask their opinion about the message of your overall paper. Also, seek responses from your supervisor if possible. Use any feedback you get to better your project further. At this point, you understand how to do a lit review. Additional tips are provided below.

Literature Review Format

Besides following the aforementioned steps, you must also consider how to format a literature review. Be sure to check with your institution or target journal about style guidelines and the specific rules of your work’s layout.  Each style has instructions regarding the major sections, in-text citations, and a literature reference page.  For example, an APA paper format is based on an “author-date” approach, in which the author’s name and publication year are cited inside the document. A reference list is included on your paper’s last page. APA literature review format is dominant in the sciences, psychology, and education fields.  In contrast, an MLA format paper follows a “researcher-page number” style accompanied by works cited page, which is common in the humanities.  A Chicago style paper requires footnotes or endnotes with a bibliography section for all sources. It is mostly used in fine arts, history, and business disciplines.

Literature Review Examples

At this point, you are ready to start writing your review. Before proceeding, it is advisable to consider an example of literature review in a research paper, thesis or dissertation in your field. Thoroughly read the samples you find to get familiar with aspects such as organization, argument presentation, and referencing sources correctly. This is an effective way of learning ways of framing and structuring your work. Additionally, going through how to write a literature review example helps you understand what is expected in this task. Also, when reading these samples, pay attention to the academic language used. Look at the following free examples: Literature review example (APA 7th Edition)

Literature review for research paper example

Thesis/dissertation literature review example

Tips on Writing a Literature Review in Research

Now that you have a well-rounded idea about how to write a literature review, read the recommendation described here as they remind you of essential points. Before proceeding, remember that you should include sources that are associated with your work directly. This helps you avoid frustrating and distracting readers or making them lose sight of your purpose. Also, once you start writing your review, stick to the previously created outline and keep these tips in mind:

• Analyze Do not just list studies, rather, examine them critically to find similarities, differences, relationships, or contradictions.
• Time management Take your time to select a topic, gather literature, evaluate, read, and write. The last part should take about half of your time, while the remainder is for the other tasks.
• Revise Anticipate revising countless times before delivering a final version.
• Presentation A literature review in a research paper, thesis or dissertation must be specific and provide concrete examples. For example, rather than “this” use “this result”. First-person references should be avoided because they signal unsupported arguments. Everything written should have a reason. Also, use short paragraphs as they are easier to read. Additionally, structure your work with headings, subheadings, and subsections to make it flow.
• Paraphrase Avoid relying too much on quoting directly from sources or one researcher. Rather, paraphrase and compare authors between themselves and with your ideas.
• References Give credit to every outside idea or language by citing their work in your paper.

Literature Review Checklist

Now that you are through with composing your literature review, it is essential to be sure that your work is ready for delivery or publication. Therefore, you must take your time and reflect on the following questions to ensure that every section is covered thoroughly. Consider this final checklist:

• checkbox I stated the reason for conducting my project and outlined its scope.
• checkbox I chose relevant and credible studies.
• checkbox I have identified recent trends.
• checkbox I have logically presented a review of literature in my research paper or dissertation.
• checkbox I organized my information based on themes/issues/methods/theories.
• checkbox I have located gaps in research and literature.
• checkbox I displayed how details supporting a topic relate to its significance.
• checkbox I wrote my literature review critically.
• checkbox I have demonstrated instances when findings contradicted each other or were inconclusive.
• checkbox I explored designs, theories, questions, models, and hypotheses.
• checkbox I highlighted each source’s importance to my theme.
• checkbox I have included an introduction, body, and conclusion.
• checkbox I have checked for grammatical issues.

Final Thoughts on Writing a Scientific Literature Review

We have provided you with all the necessary information on how to write a review of literature. Follow our step-by-step guide to identify the right keywords, evaluate sources, and select credible and relevant articles. Make sure to structure your writing clearly and logically using the key components of a literature review that we have outlined for you.  To help you further, we have included examples of literature reviews for you to check. With these simplified requirements, you are ready to start practicing and creating your own literature reviews. Remember, practice is essential to mastering this type of writing, so keep it up!

If you are looking for some quick solution, we got you covered! Go to StudyCrumb and ask our professional writers for help. Just leave a ‘ write my paper ’ notice along with requirements and get high-quality work that will bring you an A.

FAQ About Literature Reviews

1. what is a literature review in a research paper.

The literature review of a research paper is a type of academic essay that analyzes and evaluates previous or existing studies on a topic. It aims to survey readings, synthesize, and digest the obtained information. It also critically explores the data by identifying gaps in knowledge, demonstrating limitations in manuscripts, examining contradictions, and determining areas for additional research. The final piece is presented logically.

2. Where does a literature review go in a research paper?

A literature review generally comes after an introduction and before the methodology chapter of dissertations. Here, it is used to analyze relevant scholarship about a topic, ground your research paper in a specific field, and inform your data collection methods and analysis procedures.

3. How to start a literature review?

Start a literature review by describing the background of what you will analyze in your body paragraphs. There is no need to be comprehensive here. Rather, show that you clearly understand your paper’s scope. In particular, begin by conveying the established ideas and knowledge on the subject being explored to your audience.

4. What is the difference between a literature review and an annotated bibliography?

The main difference between the two is that literature reviews focus on providing an overview and analysis of existing research on a particular theme. They aim to identify the strengths and weaknesses of arguments and draw conclusions. In contrast, the purpose of an annotated bibliography is to collect sources for a specific project and offer summaries of what they are about.

5. What is the importance of a literature review?

A literature review is important because:

• It establishes a rapport with your readers They will trust you because you have examined and analyzed facts appropriately.
• Helps researchers deliver original work The entire process of conducting the assessment assists you to evade repeating something done by someone else.
• It improves your research focus Synthesizing and analyzing studies can guide and shape your investigation in new directions by providing novel insights and views on a theme.

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• Systematic Review
• Open access
• Published: 23 May 2024

Systematic literature review of real-world evidence for treatments in HR+/HER2- second-line LABC/mBC after first-line treatment with CDK4/6i

• Veronique Lambert   ORCID: orcid.org/0000-0002-6984-0038 1 ,
• Sarah Kane   ORCID: orcid.org/0009-0006-9341-4836 2   na1 ,
• Belal Howidi   ORCID: orcid.org/0000-0002-1166-7631 2   na1 ,
• Bao-Ngoc Nguyen   ORCID: orcid.org/0000-0001-6026-2270 2   na1 ,
• David Chandiwana   ORCID: orcid.org/0009-0002-3499-2565 3 ,
• Yan Wu   ORCID: orcid.org/0009-0008-3348-9232 1 ,
• Michelle Edwards   ORCID: orcid.org/0009-0001-4292-3140 3 &
• Imtiaz A. Samjoo   ORCID: orcid.org/0000-0003-1415-8055 2   na1  

BMC Cancer volume  24 , Article number:  631 ( 2024 ) Cite this article

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Cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) combined with endocrine therapy (ET) are currently recommended by the National Comprehensive Cancer Network (NCCN) guidelines and the European Society for Medical Oncology (ESMO) guidelines as the first-line (1 L) treatment for patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative, locally advanced/metastatic breast cancer (HR+/HER2- LABC/mBC). Although there are many treatment options, there is no clear standard of care for patients following 1 L CDK4/6i. Understanding the real-world effectiveness of subsequent therapies may help to identify an unmet need in this patient population. This systematic literature review qualitatively synthesized effectiveness and safety outcomes for treatments received in the real-world setting after 1 L CDK4/6i therapy in patients with HR+/ HER2- LABC/mBC.

MEDLINE®, Embase, and Cochrane were searched using the Ovid® platform for real-world evidence studies published between 2015 and 2022. Grey literature was searched to identify relevant conference abstracts published from 2019 to 2022. The review was conducted in accordance with PRISMA guidelines (PROSPERO registration: CRD42023383914). Data were qualitatively synthesized and weighted average median real-world progression-free survival (rwPFS) was calculated for NCCN/ESMO-recommended post-1 L CDK4/6i treatment regimens.

Twenty records (9 full-text articles and 11 conference abstracts) encompassing 18 unique studies met the eligibility criteria and reported outcomes for second-line (2 L) treatments after 1 L CDK4/6i; no studies reported disaggregated outcomes in the third-line setting or beyond. Sixteen studies included NCCN/ESMO guideline-recommended treatments with the majority evaluating endocrine-based therapy; five studies on single-agent ET, six studies on mammalian target of rapamycin inhibitors (mTORi) ± ET, and three studies with a mix of ET and/or mTORi. Chemotherapy outcomes were reported in 11 studies. The most assessed outcome was median rwPFS; the weighted average median rwPFS was calculated as 3.9 months (3.3-6.0 months) for single-agent ET, 3.6 months (2.5–4.9 months) for mTORi ± ET, 3.7 months for a mix of ET and/or mTORi (3.0–4.0 months), and 6.1 months (3.7–9.7 months) for chemotherapy. Very few studies reported other effectiveness outcomes and only two studies reported safety outcomes. Most studies had heterogeneity in patient- and disease-related characteristics.

Conclusions

The real-world effectiveness of current 2 L treatments post-1 L CDK4/6i are suboptimal, highlighting an unmet need for this patient population.

Peer Review reports

Introduction

Breast cancer (BC) is the most diagnosed form of cancer in women with an estimated 2.3 million new cases diagnosed worldwide each year [ 1 ]. BC is the second leading cause of cancer death, accounting for 685,000 deaths worldwide per year [ 2 ]. By 2040, the global burden associated with BC is expected to surpass three million new cases and one million deaths annually (due to population growth and aging) [ 3 ]. Numerous factors contribute to global disparities in BC-related mortality rates, including delayed diagnosis, resulting in a high number of BC cases that have progressed to locally advanced BC (LABC) or metastatic BC (mBC) [ 4 , 5 , 6 ]. In the United States (US), the five-year survival rate for patients who progress to mBC is three times lower (31%) than the overall five-year survival rate for all stages (91%) [ 6 , 7 ].

Hormone receptor (HR) positive (i.e., estrogen receptor and/or progesterone receptor positive) coupled with negative human epidermal growth factor 2 (HER2) expression is the most common subtype of BC, accounting for ∼ 60–70% of all BC cases [ 8 , 9 ]. Historically, endocrine therapy (ET) through estrogen receptor modulation and/or estrogen deprivation has been the standard of care for first-line (1 L) treatment of HR-positive/HER2-negative (HR+/HER2-) mBC [ 10 ]. However, with the approval of the cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) palbociclib in combination with the aromatase inhibitor (AI) letrozole in 2015 by the US Food and Drug Administration (FDA), 1 L treatment practice patterns have evolved such that CDK4/6i (either in combination with AIs or with fulvestrant) are currently considered the standard of care [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Other CDK4/6i (ribociclib and abemaciclib) in combination with ET are approved for the treatment of HR+/HER2- LABC/mBC; 1 L use of ribociclib in combination with an AI was granted FDA approval in March 2017 for postmenopausal women (with expanded approval in July 2018 for pre/perimenopausal women and for use in 1 L with fulvestrant for patients with disease progression on ET as well as for postmenopausal women), and abemaciclib in combination with fulvestrant was granted FDA approval in September 2017 for patients with disease progression following ET and as monotherapy in cases where disease progression occurs following ET and prior chemotherapy in mBC (with expanded approval in February 2018 for use in 1 L in combination with an AI for postmenopausal women) [ 18 , 19 , 20 , 21 ].

Clinical trials investigating the addition of CDK4/6i to ET have demonstrated significant improvement in progression-free survival (PFS) and significant (ribociclib) or numerical (palbociclib and abemaciclib) improvement in overall survival (OS) compared to ET alone in patients with HR+/HER2- advanced or mBC, making this combination treatment the recommended option in the 1 L setting [ 22 , 23 , 24 , 25 , 26 , 27 ]. However, disease progression occurs in a significant portion of patients after 1 L CDK4/6i treatment [ 28 ] and the optimal treatment sequence after progression on CDK4/6i remains unclear [ 29 ]. At the time of this review (literature search conducted December 14, 2022), guidelines by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO) recommend various options for the treatment of HR+/HER2- advanced BC in the second-line (2 L) setting, including fulvestrant monotherapy, mammalian target of rapamycin inhibitors (mTORi; e.g., everolimus) ± ET, alpelisib + fulvestrant (if phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha mutation positive [PIK3CA-m+]), poly-ADP ribose polymerase inhibitors (PARPi) including olaparib or talazoparib (if breast cancer gene/partner and localizer of BRCA2 positive [BRCA/PALB2m+]), and chemotherapy (in cases when a visceral crisis is present) [ 15 , 16 ]. CDK4/6i can also be used in 2 L [ 16 , 30 ]; however, limited data are available to support CDK4/6i rechallenge after its use in the 1 L setting [ 15 ]. Depending on treatments used in the 1 L and 2 L settings, treatment in the third-line setting is individualized based on the patient’s response to prior treatments, tumor load, duration of response, and patient preference [ 9 , 15 ]. Understanding subsequent treatments after 1 L CDK4/6i, and their associated effectiveness, is an important focus in BC research.

Treatment options for HR+/HER2- LABC/mBC continue to evolve, with ongoing research in both clinical trials and in the real-world setting. Real-world evidence (RWE) offers important insights into novel therapeutic regimens and the effectiveness of treatments for HR+/HER2- LABC/mBC. The effectiveness of the current treatment options following 1 L CDK4/6i therapy in the real-world setting highlights the unmet need in this patient population and may help to drive further research and drug development. In this study, we conducted a systematic literature review (SLR) to qualitatively summarize the effectiveness and safety of treatment regimens in the real-world setting after 1 L treatment with CDK4/6i in patients with HR+/HER2- LABC/mBC.

Literature search

An SLR was performed in accordance with the Cochrane Handbook for Systematic Reviews of Interventions [ 31 ] and reported in alignment with the Preferred Reporting Items for Systematic Literature Reviews and Meta-Analyses (PRISMA) statement [ 32 ] to identify all RWE studies assessing the effectiveness and safety of treatments used for patients with HR+/HER2- LABC/mBC following 1 L CDK4/6i therapy and received subsequent treatment in 2 L and beyond (2 L+). The Ovid® platform was used to search MEDLINE® (including Epub Ahead of Print and In-Process, In-Data-Review & Other Non-Indexed Citations), Ovid MEDLINE® Daily, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews by an experienced medical information specialist. The MEDLINE® search strategy was peer-reviewed independently by a senior medical information specialist before execution using the Peer Review of Electronic Search Strategies (PRESS) checklist [ 33 ]. Searches were conducted on December 14, 2022. The review protocol was developed a priori and registered with the International Prospective Register of Systematic Review (PROSPERO; CRD42023383914) which outlined the population, intervention, comparator, outcome, and study design (PICOS) criteria and methodology used to conduct the review (Table  1 ).

Search strategies utilized a combination of controlled vocabulary (e.g., “HER2 Breast Cancer” or “HR Breast Cancer”) and keywords (e.g., “Retrospective studies”). Vocabulary and syntax were adjusted across databases. Published and validated filters were used to select for study design and were supplemented using additional medical subject headings (MeSH) terms and keywords to select for RWE and nonrandomized studies [ 34 ]. No language restrictions were included in the search strategy. Animal-only and opinion pieces were removed from the results. The search was limited to studies published between January 2015 and December 2022 to reflect the time at which FDA approval was granted for the first CDK4/6i agent (palbociclib) in combination with AI for the treatment of LABC/mBC [ 35 ]. Further search details are presented in Supplementary Material 1 .

Grey literature sources were also searched to identify relevant abstracts and posters published from January 2019 to December 2022 for prespecified relevant conferences including ESMO, San Antonio Breast Cancer Symposium (SABCS), American Society of Clinical Oncology (ASCO), the International Society for Pharmacoeconomics and Outcomes Research (ISPOR US), and the American Association for Cancer Research (AACR). A search of ClinicalTrials.gov was conducted to validate the findings from the database and grey literature searches.

Study selection, data extraction & weighted average calculation

Studies were screened for inclusion using DistillerSR Version 2.35 and 2.41 (DistillerSR Inc. 2021, Ottawa, Canada) by two independent reviewers based on the prespecified PICOS criteria (Table  1 ). A third reviewer was consulted to resolve any discrepancies during the screening process. Studies were included if they reported RWE on patients aged ≥ 18 years with HR+/HER2- LABC/mBC who received 1 L CDK4/6i treatment and received subsequent treatment in 2 L+. Studies were excluded if they reported the results of clinical trials (i.e., non-RWE), were published in any language other than English, and/or were published prior to 2015 (or prior to 2019 for conference abstracts and posters). For studies that met the eligibility criteria, data relating to study design and methodology, details of interventions, patient eligibility criteria and baseline characteristics, and outcome measures such as efficacy, safety, tolerability, and patient-reported outcomes (PROs), were extracted (as available) using a Microsoft Excel®-based data extraction form (Microsoft Corporation, WA, USA). Data extraction was performed by a single reviewer and was confirmed by a second reviewer. Multiple publications identified for the same RWE study, patient population, and setting that reported data for the same intervention were linked and extracted as a single publication. Weighted average median real-world progression-free survival (rwPFS) values were calculated by considering the contribution to the median rwPFS of each study proportional to its respective sample size. These weighted values were then used to compute the overall median rwPFS estimate.

Quality assessment

The Newcastle-Ottawa scale (NOS) for nonrandomized (cohort) studies was used to assess the risk of bias for published, full-text studies [ 36 ]. The NOS allocates a maximum of nine points for the least risk of bias across three domains: (1) Formation of study groups (four points), (2) Comparability between study groups (two points), (3) Outcome ascertainment (three points). NOS scores can be categorized in three groups: very high risk of bias (0 to 3 points), high risk of bias (4 to 6), and low risk of bias (7 to 9) [ 37 ]. Risk of bias assessment was performed by one reviewer and validated by a second independent reviewer to verify accuracy. Due to limited methodological data by which to assess study quality, risk of bias assessment was not performed on conference abstracts or posters. An amendment to the PROSPERO record (CRD42023383914) for this study was submitted in relation to the quality assessment method (specifying usage of the NOS).

The database search identified 3,377 records; after removal of duplicates, 2,759 were screened at the title and abstract stage of which 2,553 were excluded. Out of the 206 reports retrieved and assessed for eligibility, an additional 187 records were excluded after full-text review; most of these studies were excluded for having patients with mixed lines of CDK4/6i treatment (i.e., did not receive CDK4/6i exclusively in 1 L) (Fig.  1 and Table S1 ). The grey literature search identified 753 records which were assessed for eligibility; of which 752 were excluded mainly due to the population not meeting the eligibility criteria (Fig.  1 ). In total, the literature searches identified 20 records (9 published full-text articles and 11 conference abstracts/posters) representing 18 unique RWE studies that met the inclusion criteria. The NOS quality scores for the included full-text articles are provided in Table S2 . The scores ranged from four to six points (out of a total score of nine) and the median score was five, indicating that all the studies suffered from a high risk of bias [ 37 ].

Most studies were retrospective analyses of chart reviews or medical registries, and all studies were published between 2017 and 2022 (Table S3 ). Nearly half of the RWE studies (8 out of 18 studies) were conducted in the US [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ], while the remaining studies included sites in Canada, China, Germany, Italy, Japan, and the United Kingdom [ 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. Sample sizes ranged from as few as 4 to as many as 839 patients across included studies, with patient age ranging from 26 to 86 years old.

Although treatment characteristics in the 1 L setting were not the focus of the present review, these details are captured in Table S3 . Briefly, several RWE studies reported 1 L CDK4/6i use in combination with ET (8 out of 18 studies) or as monotherapy (2 out of 18 studies) (Table S3 ). Treatments used in combination with 1 L CDK4/6i included letrozole, fulvestrant, exemestane, and anastrozole. Where reported (4 out of 18 studies), palbociclib was the most common 1 L CDK4/6i treatment. Many studies (8 out of 18 studies) did not report which specific CDK4/6i treatment(s) were used in 1 L or if its administration was in combination or monotherapy.

Characteristics of treatments after 1 L CDK4/6i therapy

Across all studies included in this review, effectiveness and safety data were only available for treatments administered in the 2 L setting after 1 L CDK4/6i treatment. No studies were identified that reported outcomes for patients treated in the third-line setting or beyond after 1 L CDK4/6i treatment. All 18 studies reported effectiveness outcomes in 2 L, with only two of these studies also describing 2 L safety outcomes. The distribution of outcomes reported in these studies is provided in Table S4 . Studies varied in their reporting of outcomes for 2 L treatments; some studies reported outcomes for a group of 2 L treatments while others described independent outcomes for specific 2 L treatments (i.e., everolimus, fulvestrant, or chemotherapy agents such as eribulin mesylate) [ 42 , 45 , 50 , 54 , 55 ]. Due to the heterogeneity in treatment classes reported in these studies, this data was categorized (as described below) to align with the guidelines provided by NCCN and ESMO [ 15 , 16 ]. The treatment class categorizations for the purpose of this review are: single-agent ET (patients who exclusively received a single-agent ET after 1 L CDK4/6i treatment), mTORi ± ET (patients who exclusively received an mTORi with or without ET after 1 L CDK4/6i treatment), mix of ET and/or mTORi (patients who may have received only ET, only mTORi, and/or both treatments but the studies in this group lacked sufficient information to categorize these patients in the “single-agent ET” or “mTOR ± ET” categories), and chemotherapy (patients who exclusively received chemotherapy after 1 L CDK4/6i treatment). Despite ESMO and NCCN guidelines indicating that limited evidence exists to support rechallenge with CDK4/6i after 1 L CDK4/6i treatment [ 15 , 16 ], two studies reported outcomes for this treatment approach. Data for such patients were categorized as “ CDK4/6i ± ET ” as it was unclear how many patients receiving CDK4/6i rechallenge received concurrent ET. All other patient groups that lacked sufficient information or did not report outcome/safety data independently (i.e., grouped patients with mixed treatments) to categorize as one of the treatment classes described above were grouped as “ other ”.

The majority of studies reported effectiveness outcomes for endocrine-based therapy after 1 L CDK4/6i treatment; five studies for single-agent ET, six studies for mTORi ± ET, and three studies for a mix of ET and/or mTORi (Fig.  2 ). Eleven studies reported effectiveness outcomes for chemotherapy after 1 L CDK4/6i treatment, and only two studies reported effectiveness outcomes for CDK4/6i rechallenge ± ET. Eight studies that described effectiveness outcomes were grouped into the “other” category. Safety data was only reported in two studies: one study evaluating the chemotherapy agent eribulin mesylate and one evaluating the mTORi everolimus.

Effectiveness outcomes

Real-world progression-free survival

Median rwPFS was described in 13 studies (Tables  2 and Table S5 ). Across the 13 studies, the median rwPFS ranged from 2.5 months [ 49 ] to 17.3 months [ 39 ]. Out of the 13 studies reporting median rwPFS, 10 studies reported median rwPFS for a 2 L treatment recommended by ESMO and NCCN guidelines, which ranged from 2.5 months [ 49 ] to 9.7 months [ 45 ].

Weighted average median rwPFS was calculated for 2 L treatments recommended by both ESMO and NCCN guidelines (Fig.  3 ). The weighted average median rwPFS for single-agent ET was 3.9 months ( n  = 92 total patients) and was derived using data from two studies reporting median rwPFS values of 3.3 months ( n  = 70) [ 38 ] and 6.0 months ( n  = 22) [ 40 ]. For one study ( n  = 7) that reported outcomes for single agent ET, median rwPFS was not reached during the follow-up period; as such, this study was excluded from the weighted average median rwPFS calculation [ 49 ].

The weighted average median rwPFS for mTORi ± ET was 3.6 months ( n  = 128 total patients) and was derived based on data from 3 studies with median rwPFS ranging from 2.5 months ( n  = 4) [ 49 ] to 4.9 months ( n  = 25) [ 54 ] (Fig.  3 ). For patients who received a mix of ET and/or mTORi but could not be classified into the single-agent ET or mTORi ± ET treatment classes, the weighted average median rwPFS was calculated to be 3.7 months ( n  = 17 total patients). This was calculated based on data from two studies reporting median rwPFS values of 3.0 months ( n  = 5) [ 46 ] and 4.0 months ( n  = 12) [ 49 ]. Notably, one study of patients receiving ET and/or everolimus reported a median rwPFS duration of 3.0 months; however, this study was excluded from the weighted average median rwPFS calculation for the ET and/or mTORi class as the sample size was not reported [ 53 ].

The weighted average median rwPFS for chemotherapy was 6.1 months ( n  = 499 total patients), calculated using data from 7 studies reporting median rwPFS values ranging from 3.7 months ( n  = 249) [ 38 ] to 9.7 months ( n  = 121) [ 45 ] (Fig.  3 ). One study with a median rwPFS duration of 5.6 months was not included in the weighted average median rwPFS calculation as the study did not report the sample size [ 53 ]. A second study was excluded from the calculation since the reported median rwPFS was not reached during the study period ( n  = 7) [ 41 ].

Although 2 L CDK4/6i ± ET rechallenge lacks sufficient information to support recommendation by ESMO and NCCN guidelines, the limited data currently available for this treatment have shown promising results. Briefly, two studies reported median rwPFS for CDK4/6i ± ET with values of 8.3 months ( n  = 302) [ 38 ] and 17.3 months ( n  = 165) (Table  2 ) [ 39 ]. The remaining median rwPFS studies reported data for patients classified as “Other” (Table S5 ). The “Other” category included median rwPFS outcomes from seven studies, and included a myriad of treatments (e.g., ET, mTOR + ET, chemotherapy, CDK4/6i + ET, alpelisib + fulvestrant, chidamide + ET) for which disaggregated median rwPFS values were not reported.

Overall survival

Median OS for 2 L treatment was reported in only three studies (Table  2 ) [ 38 , 42 , 43 ]. Across the three studies, the 2 L median OS ranged from 5.2 months ( n  = 3) [ 43 ] to 35.7 months ( n  = 302) [ 38 ]. Due to the lack of OS data in most of the studies, weighted averages could not be calculated. No median OS data was reported for the single-agent ET treatment class whereas two studies reported median OS for the mTORi ± ET treatment class, ranging from 5.2 months ( n  = 3) [ 43 ] to 21.8 months ( n  = 54) [ 42 ]. One study reported 2 L median OS of 24.8 months for a single patient treated with chemotherapy [ 43 ]. The median OS data in the CDK4/6i ± ET rechallenge group was 35.7 months ( n  = 302) [ 38 ].

Patient mortality was reported in three studies [ 43 , 44 , 45 ]. No studies reported mortality for the single-agent ET treatment class and only one study reported this outcome for the mTORi ± ET treatment class, where 100% of patients died ( n  = 3) as a result of rapid disease progression [ 43 ]. For the chemotherapy class, one study reported mortality for one patient receiving 2 L capecitabine [ 43 ]. An additional study reported eight deaths (21.7%) following 1 L CDK4/6i treatment; however, this study did not disclose the 2 L treatments administered to these patients [ 44 ].

Other clinical endpoints

The studies included limited information on additional clinical endpoints; two studies reported on time-to-discontinuation (TTD), two reported on duration of response (DOR), and one each on time-to-next-treatment (TTNT), time-to-progression (TTP), objective response rate (ORR), clinical benefit rate (CBR), and stable disease (Tables  2 and Table S5 ).

Safety, tolerability, and patient-reported outcomes

Safety and tolerability data were reported in two studies [ 40 , 45 ]. One study investigating 2 L administration of the chemotherapy agent eribulin mesylate reported 27 patients (22.3%) with neutropenia, 3 patients (2.5%) with febrile neutropenia, 10 patients (8.3%) with peripheral neuropathy, and 14 patients (11.6%) with diarrhea [ 45 ]. Of these, neutropenia of grade 3–4 severity occurred in 9 patients (33.3%) [ 45 ]. A total of 55 patients (45.5%) discontinued eribulin mesylate treatment; 1 patient (0.83%) discontinued treatment due to adverse events [ 45 ]. Another study reported that 5 out of the 22 patients receiving the mTORi everolimus combined with ET in 2 L (22.7%) discontinued treatment due to toxicity [ 40 ]. PROs were not reported in any of the studies included in the SLR.

The objective of this study was to summarize the existing RWE on the effectiveness and safety of therapies for patients with HR+/HER2- LABC/mBC after 1 L CDK4/6i treatment. We identified 18 unique studies reporting specifically on 2 L treatment regimens after 1 L CDK4/6i treatment. The weighted average median rwPFS for NCCN- and ESMO- guideline recommended 2 L treatments ranged from 3.6 to 3.9 months for ET-based treatments and was 6.1 months when including chemotherapy-based regimens. Treatment selection following 1 L CDK4/6i therapy remains challenging primarily due to the suboptimal effectiveness or significant toxicities (e.g., chemotherapy) associated with currently available options [ 56 ]. These results highlight that currently available 2 L treatments for patients with HR+/HER2- LABC/mBC who have received 1 L CDK4/6i are suboptimal, as evidenced by the brief median rwPFS duration associated with ET-based treatments, or notable side effects and toxicity linked to chemotherapy. This conclusion is aligned with a recent review highlighting the limited effectiveness of treatment options for HR+/HER2- LABC/mBC patients post-CDK4/6i treatment [ 56 , 57 ]. Registrational trials which have also shed light on the short median PFS of 2–3 months achieved by ET (i.e., fulvestrant) after 1 L CDK4/6i therapy emphasize the need to develop improved treatment strategies aimed at prolonging the duration of effective ET-based treatment [ 56 ].

The results of this review reveal a paucity of additional real-world effectiveness and safety evidence after 1 L CDK4/6i treatment in HR+/HER2- LABC/mBC. OS and DOR were only reported in two studies while other clinical endpoints (i.e., TTD, TTNT, TTP, ORR, CBR, and stable disease) were only reported in one study each. Similarly, safety and tolerability data were only reported in two studies each, and PROs were not reported in any study. This hindered our ability to provide a comprehensive assessment of real-world treatment effectiveness and safety following 1 L CDK4/6i treatment. The limited evidence may be due to the relatively short period of time that has elapsed since CDK4/6i first received US FDA approval for 1 L treatment of HR+/HER2- LABC/mBC (2015) [ 35 ]. As such, almost half of our evidence was informed by conference abstracts. Similarly, no real-world studies were identified in our review that reported outcomes for treatments in the third- or later-lines of therapy after 1 L CDK4/6i treatment. The lack of data in this patient population highlights a significant gap which limits our understanding of the effectiveness and safety for patients receiving later lines of therapy. As more patients receive CDK4/6i therapy in the 1 L setting, the number of patients requiring subsequent lines of therapy will continue to grow. Addressing this data gap over time will be critical to improve outcomes for patients with HR+/HER2- LABC/mBC following 1 L CDK4/6i therapy.

There are several strengths of this study, including adherence to the guidelines outlined in the Cochrane Handbook to ensure a standardized and reliable approach to the SLR [ 58 ] and reporting of the SLR following PRISMA guidelines to ensure transparency and reproducibility [ 59 ]. Furthermore, the inclusion of only RWE studies allowed us to assess the effectiveness of current standard of care treatments outside of a controlled environment and enabled us to identify an unmet need in this patient population.

This study had some notable limitations, including the lack of safety and additional effectiveness outcomes reported. In addition, the dearth of studies reporting PROs is a limitation, as PROs provide valuable insight into the patient experience and are an important aspect of assessing the impact of 2 L treatments on patients’ quality of life. The studies included in this review also lacked consistent reporting of clinical characteristics (e.g., menopausal status, sites of metastasis, prior surgery) making it challenging to draw comprehensive conclusions or comparisons based on these factors across the studies. Taken together, there exists an important gap in our understanding of the long-term management of patients with HR+/HER2- LABC/mBC. Additionally, the effectiveness results reported in our evidence base were informed by small sample sizes; many of the included studies reported median rwPFS based on less than 30 patients [ 39 , 40 , 41 , 46 , 49 , 51 , 60 ], with two studies not reporting the sample size at all [ 47 , 53 ]. This may impact the generalizability and robustness of the results. Relatedly, the SLR database search was conducted in December 2022; as such, novel agents (e.g., elacestrant and capivasertib + fulvestrant) that have since received FDA approval for the treatment of HR+/HER2- LABC/mBC may impact current 2 L rwPFS outcomes [ 61 , 62 ]. Finally, relative to the number of peer-reviewed full-text articles, this SLR identified eight abstracts and one poster presentation, comprising half (50%) of the included unique studies. As conference abstracts are inherently limited by how much content that can be described due to word limit constraints, this likely had implications on the present synthesis whereby we identified a dearth of real-world effectiveness outcomes in patients with HR+/HER2- LABC/mBC treated with 1 L CDK4/6i therapy.

Future research in this area should aim to address the limitations of the current literature and provide a more comprehensive understanding of optimal sequencing of effective and safe treatment for patients following 1 L CDK4/6i therapy. Specifically, future studies should strive to report robust data related to effectiveness, safety, and PROs for patients receiving 2 L treatment after 1 L CDK4/6i therapy. Future studies should also aim to understand the mechanism underlying CDK4/6i resistance. Addressing these gaps in knowledge may improve the long-term real-world management of patients with HR+/HER2- LABC/mBC. A future update of this synthesis may serve to capture a wider breadth of full-text, peer-reviewed articles to gain a more robust understanding of the safety, effectiveness, and real-world treatment patterns for patients with HR+/HER2- LABC/mBC. This SLR underscores the necessity for ongoing investigation and the development of innovative therapeutic approaches to address these gaps and improve patient outcomes.

This SLR qualitatively summarized the existing real-world effectiveness data for patients with HR+/HER2- LABC/mBC after 1 L CDK4/6i treatment. Results of this study highlight the limited available data and the suboptimal effectiveness of treatments employed in the 2 L setting and underscore the unmet need in this patient population. Additional studies reporting effectiveness and safety outcomes, in addition to PROs, for this patient population are necessary and should be the focus of future research.

PRISMA flow diagram. *Two included conference abstracts reported the same information as already included full-text reports, hence both conference abstracts were not identified as unique. Abbreviations: 1 L = first-line; AACR = American Association of Cancer Research; ASCO = American Society of Clinical Oncology; CDK4/6i = cyclin-dependent kinase 4/6 inhibitor; ESMO = European Society for Medical Oncology; ISPOR = Professional Society for Health Economics and Outcomes Research; n = number of studies; NMA = network meta-analysis; pts = participants; SABCS = San Antonio Breast Cancer Symposium; SLR = systematic literature review.

Number of studies reporting effectiveness outcomes exclusively for each treatment class. *Studies that lack sufficient information on effectiveness outcomes to classify based on the treatment classes outlined in the legend above. Abbreviations: CDK4/6i = cyclin-dependent kinase 4/6 inhibitor; ET = endocrine therapy; mTORi = mammalian target of rapamycin inhibitor.

Weighted average median rwPFS for 2 L treatments (recommended in ESMO/NCCN guidelines) after 1 L CDK4/6i treatment. Circular dot represents weighted average median across studies. Horizontal bars represent the range of values reported in these studies. Abbreviations: CDK4/6i = cyclin-dependent kinase 4/6 inhibitor; ESMO = European Society for Medical Oncology; ET = endocrine therapy, mTORi = mammalian target of rapamycin inhibitor; n = number of patients; NCCN = National Comprehensive Cancer Network; rwPFS = real-world progression-free survival.

Data availability

All data generated or analyzed during this study are included in this published article [and its supplementary information files]. This study is registered with PROSPERO (CRD42023383914).

Abbreviations

Second-line

Second-line treatment setting and beyond

American Association of Cancer Research

Aromatase inhibitor

American Society of Clinical Oncology

• Breast cancer

breast cancer gene/partner and localizer of BRCA2 positive

Clinical benefit rate

Cyclin-dependent kinase 4/6 inhibitor

Complete response

Duration of response

European Society for Medical Oncology

Food and Drug Administration

Human epidermal growth factor receptor 2

Human epidermal growth factor receptor 2 negative

Hormone receptor

Hormone receptor positive

Professional Society for Health Economics and Outcomes Research

Locally advanced breast cancer

Metastatic breast cancer

Medical Literature Analysis and Retrieval System Online

Medical subject headings

Mammalian target of rapamycin inhibitor

National Comprehensive Cancer Network

Newcastle Ottawa Scale

Objective response rate

Poly-ADP ribose polymerase inhibitor

Progression-free survival

Population, Intervention, Comparator, Outcome, Study Design

Partial response

Preferred Reporting Items for Systematic Literature Reviews and Meta-Analyses

Patient-reported outcomes

• Real-world evidence

San Antonio Breast Cancer Symposium

• Systematic literature review

Time-to-discontinuation

Time-to-next-treatment

Time-to-progression

United States

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Acknowledgements

The authors would like to acknowledge Joanna Bielecki who developed, conducted, and documented the database searches.

This study was funded by Pfizer Inc. (New York, NY, USA) and Arvinas (New Haven, CT, USA).

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Sarah Kane, Belal Howidi, Bao-Ngoc Nguyen and Imtiaz A. Samjoo contributed equally to this work.

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VL, IAS, SK, BH, BN, DC, YW, and ME participated in the conception and design of the study. IAS, SK, BH and BN contributed to the literature review, data collection, analysis, and interpretation of the data. VL, IAS, SK, BH, BN, DC, YW, and ME contributed to the interpretation of the data and critically reviewed for the importance of intellectual content for the work. VL, IAS, SK, BH, BN, DC, YW, and ME were responsible for drafting or reviewing the manuscript and for providing final approval. VL, IAS, SK, BH, BN, DC, YW, and ME meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship for this article, take responsibility for the integrity of the work, and have given their approval for this version to be published.

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The authors of this manuscript declare that the research presented was funded by Pfizer Inc. and Arvinas. While the support from Pfizer Inc. and Arvinas was instrumental in facilitating this research, the authors affirm that their interpretation of the data and the content of this manuscript were conducted independently and without bias to maintain the transparency and integrity of the research. IAS, SK, BH, and BN are employees of EVERSANA, Canada, which was a paid consultant to Pfizer in connection with the development of this manuscript.

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Lambert, V., Kane, S., Howidi, B. et al. Systematic literature review of real-world evidence for treatments in HR+/HER2- second-line LABC/mBC after first-line treatment with CDK4/6i. BMC Cancer 24 , 631 (2024). https://doi.org/10.1186/s12885-024-12269-8

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Wandering spleen presenting in the form of right sided pelvic mass and pain in a patient with AD-PCKD: a case report and review of the literature

• Yitagesu aberra shibiru   ORCID: orcid.org/0000-0003-3645-9115 1 ,
• Sahlu wondimu 1 &
• Wassie almaw 1  

Journal of Medical Case Reports volume  18 , Article number:  259 ( 2024 ) Cite this article

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Wandering spleen is a rare clinical entity in which the spleen is hypermobile and migrate from its normal left hypochondriac position to any other abdominal or pelvic position as a result of absent or abnormal laxity of the suspensory ligaments (Puranik in Gastroenterol Rep 5:241, 2015, Evangelos in Am J Case Rep. 21, 2020) which in turn is due to either congenital laxity or precipitated by trauma, pregnancy, or connective tissue disorder (Puranik in Gastroenterol Rep 5:241, 2015, Jawad in Cureus 15, 2023). It may be asymptomatic and accidentally discovered for imaging done for other reasons or cause symptoms as a result of torsion of its pedicle and infarction or compression on adjacent viscera on its new position. It needs to be surgically treated upon discovery either by splenopexy or splectomy based on whether the spleen is mobile or not.

Case presentation

We present a case of 39 years old female Ethiopian patient who presented to us complaining constant lower abdominal pain especially on the right side associated with swelling of one year which got worse over the preceding few months of her presentation to our facility. She is primiparous with delivery by C/section and a known case of HIV infection on HAART. Physical examination revealed a right lower quadrant well defined, fairly mobile and slightly tender swelling. Hematologic investigations are unremarkable. Imaging with abdominopelvic U/S and CT-scan showed a predominantly cystic, hypo attenuating right sided pelvic mass with narrow elongated attachment to pancreatic tail and absent spleen in its normal position. CT also showed multiple different sized purely cystic lesions all over both kidneys and the pancreas compatible with AD polycystic kidney and pancreatic disease.

With a diagnosis of wandering possibly infarcted spleen, she underwent laparotomy, the finding being a fully infarcted spleen located on the right half of the upper pelvis with twisted pedicle and dense adhesions to the adjacent distal ileum and colon. Release of adhesions and splenectomy was done. Her post-operative course was uneventful.

Wandering spleen is a rare clinical condition that needs to be included in the list of differential diagnosis in patients presenting with lower abdominal and pelvic masses. As we have learnt from our case, a high index of suspicion is required to detect it early and intervene by doing splenopexy and thereby avoiding splenectomy and its related complications.

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Introduction

Wandering spleen is a rare clinical entity characterized by hypermobility of the spleen as a result of absence or abnormal laxity of its suspensory ligaments which in turn can be congenital or precipitated by a number of risk factors like repeated pregnancy, trauma, surgery or connective tissue disorder. The spleen therefore migrates from its normal left hypochondriac position, to other parts of the peritoneal cavity especially the pelvis [ 3 ]. Since the first case report in 1667, there have been less than 600 cases reported in the literature so far [ 1 , 3 ].

Wandering spleen can have different clinical presentations ranging from asymptomatic incidental finding on imaging to features of acute abdomen as a result of complete torsion of the pedicle and total infarction of the spleen or complete obstruction of adjacent hollow viscus due to pressure effect. Less dramatic presentation includes chronic lower abdominal pain, swelling and symptoms of partial obstruction of bowel especially of the colon [ 3 , 4 , 5 , 6 ].

Diagnosis is confirmed by imaging usually abdominal ultrasound or CT which reveals that the spleen is absent from its normal anatomical position but seen somewhere else in the new location within the peritoneal cavity [ 3 , 9 , 10 ]. Once diagnosed, surgical intervention is required either by splenopexy or splenectomy depending on the viability of the organ [ 3 , 5 ] and can be done laparoscopically or by laparotomy.

Owing to its rarity, a high index of suspicion is required and this condition should always be considered as a possible differential diagnosis in patients presenting with lower abdominal swelling and pain. We present this case to share our experience in diagnosing and managing such a rare pathology and once again bring it to the attention of fellow clinicians handling this sort of abdominal conditions.

Case summary

Our patient is a 39 years old female Primi-para Ethiopian, who presented with lower abdominal dull aching pain of one-year duration which got worse over the last few months associated with right lower abdominal swelling, easy fatigability, LGIF, loss of appetite and weight. She is a known case of RVI on HAART for the past 18yrs and hypertensive for the last 8 years for which she was taking enalapril and atenolol. Her only child was delivered by C/section 10 years ago.

On examination , she looked chronically sick with her vitals in the normal range. The abdomen was flat with a lower midline surgical scar and a visible round mass on the right paraumblical and lower quadrant areas. The mass was well defined, smooth surfaced, slightly tender and mobile (Fig.  1 —black arrow).

Black arrow shows the splenic mass, red arrow shows the stomach, cyan arrow shows previous CS scar

Her hematologic tests revealed WBC of 8.7 × 103, Hgb of 12.3 and PLT count of 544 × 10 3 . Serum electrolyte and liver function tests were all in the normal range. Creatinine was 1.4 mg/dl.

Abdominal ultrasound

Multiple bilateral renal, liver and pancreatic cysts. An ehcocomplex mainly hypoechoic, 13 cmx8cm well defined right sided abdomino-pelvic mass, with absent color Doppler flow. Spleen was not visualized in its normal anatomic site.

Contrast enhanced abdomino-pelvic CT

Described the mass as a hypoattenuating, well circumscribed lesion with no contrast enhancement located at right abdomino pelvic cavity (Fig.  2 ). Its long torsed pedicle could be traced to the region of the tail of the pancreas and the spleen was missing from its normal location. (Fig.  3 ) Majority of the renal parenchyma is almost replaced with different sized cystic lesions with imperceptible wall causing bilateral renal enlargement. (Fig.  3 ) The liver and the pancreas too is filled with similar cysts. The portal vein were not visualized and replaced by periportal enlarged collateral vessels. (Figs.  3 , 4 ).

Infarcted spleen

Absent spleen in the splenic fossa

Spleen seen in the abdomino-pelvic cavity

With a diagnosis of wandering spleen located in the right abdomino pelvic region with torsion of the pedicle and infarction, she was admitted and underwent laparotomy. Intraoperatively, dense adhesion encountered between the anterior abdominal wall, omentum, the wandering spleen and small bowel. The spleen was whitish, distended and grossly infarcted with its long stalk torsed > 360°. (Fig.  5 ) Adhesions were gently released and splenectomy done. The splenic mass was sent for biopsy.

The intra-op picture of our patient upon exploration

She was discharged on the 3rd postoperative day and her post-operative course was uneventful. She was seen after a month on follow up clinic with no report of complication. Her biopsy result showed splenic tissue. She got her pentavelant vaccine on the third week.

Wandering spleen is a rare clinical entity characterized by splenic hypermobility from its left hypochondriac position to any other abdominal or pelvic position caused by absent or abnormal laxity of the suspensory ligaments [ 1 , 2 ].

The first case of wandering spleen was reported by Von Horne in 1667. So far less than 600 cases are reported world wide [ 1 , 3 ].

Anatomically a normal spleen is found in the left hypochondriac region suspended by ligaments to the stomach, kidney, pancreas, colon and left hemi-diaphram by the gastrosplenic, splenorenal, pancreaticosplenic, splenocolic, splenophreni ligaments and presplenic folds [ 1 ]. Our patient presented with RLQ palpable abdominal mass which is against the commonest presentation being in the LLQ of the abdomen (Fig.  1 ).

It could result from either a developmental failure of the embryonic septum transversum to fuse properly with the posterior abdominal wall which results in absent/lax ligaments [ 4 ] or from acquired conditions that result in lax suspensory ligaments as in pregnancy or connective tissue disorders [ 3 ]. The spleen is found in any quadrant of the abdomen or the pelvis though mostly in the left quadrants attached only by a long and loose vascular pedicle. Our patient presented with RLQ mass.

It is mostly seen in multiparous women [ 4 ] though the incidence is found to be nearly equal in both sexes in the prepubertal age group [ 3 ]. Our patient was a Para 1 mother and presented with 01 year history of abdominal pain which got worse in the past 06 months. Otherwise she had no any other pressure symptoms. She had visible umbilical area mass which was mobile up on examination

Wandering spleen can have different presentation ranging from asymptomatic incidental finding on imaging or upon surgical exploration for other surgical conditions to a presentation that mimics acute abdomen [ 3 , 5 ]. Mostly it presents as an on and of type acute/ subacute non-specific abdominal pain due to torsion and spontaneous de-torsion of the loose splenic pedicle [ 3 , 4 ]. This chronic torsion results in congestion and splenomegaly [ 3 , 5 ]. Hence patients could have palpable mobile mass [ 6 ] which is the typical presentation of this patient. The other presentations are usually related to the mass effect of the enlarged spleen and patients could present with GOO, bowel obstruction, pancreatitis and urinary symptoms [ 3 , 6 ].

In some cases it is reported to be associated with some other disorders like gastric volvulus [ 7 ] and distal pancreatic volvulus [ 8 ].

Ultrasound is one of the imaging modalities to investigate patients whom we suspect had wandering spleen. It usually shows absent spleen in the splenic fossa and a comma shaped spleen in the abdomen or pelvis [ 9 ]. Doppler study might help us see the vascular condition and ads up to a better preoperative plan. CT scan shows absence of the spleen in the left upper quadrant, ovoid or comma-shaped abdominal mass, enlarged spleen, a whirled appearance of non-enhancing splenic vessels and signs of splenic hypo-perfusion: homogenous or heterogeneous decreased enhancement depending on the degree of infarction [ 3 , 9 , 10 ].

Our patient was scanned with US and showed 13*8 cm large midline abdomino-pelvic well defined oval mass which was predominantly solid with areas of cystic component with absent color Doppler flow. Otherwise the spleen was not visualized in the splenic fossa. Bilateral kidney and liver has multiple different sized cystic lesions. With this image Abdomino-pelvic CT was done and shows spleen is located in the lower abdomen and appears to have torsed vascular pedicle and the whole splenic parenchyma is hypodense and no enhancement seen. Majority of the renal parenchyma is almost replaced with different sized cystic lesions with imperceptible wall causing bilateral renal enlargement. The whole liver is filled with cystic lesions with imperceptible wall. The portal veins were not visualized and replaced by periportal enlarged collateral vessels (Figs.  6 , 7 ).

Usually surgical management is the rule once a patient is diagnosed with wandering spleen [ 3 , 5 ]. Most patients; 65% as reported in some studies will have torsion of the vascular pedicle at some point of their life [ 5 , 6 ]. Hence splenopexy or splenectomy shall be considered when a wandering spleen is found incidentally up on surgical exploration for some other purposes [ 6 ]. Complicated wandering spleen like infarcted, signs of hypersplenism, huge in size and splenic vein thrombosis needs splenectomy while others can be managed with splenopexy [ 3 , 5 , 6 ]. Nowadays though laparoscopic technique is the gold standard, open technique can be used for splenopexy and splenectomy [ 3 , 5 ].

Partial infraction of a wandering spleen might necessitate partial splenectomy and splenopexy or splenectomy and splenic implantation [ 6 , 11 ].

The spleen might get fixed by different methods [ 8 , 9 ].

Simple splenic fixation involves simple tacking the splenic capsule to the peritoneum

Retroperitoneal pouch splenopexy- Tissue [ 11 , 12 ]/Mesh splenopexy (sandwich technique) [ 13 ].

Omental and peritoneal pouch splenic fixation [ 14 ].

In our case, Spleen was absent from the normal anatomic splenic fossa and the spleen in the abdomino-pelvic area looks infarcted. Hence she was managed with splenectomy and the patient was extubated on table and having a stable postoperative course .

Wandering spleen is a rare form of splenic pathology. Such a rare pathology presents commonly as an acute torsion with infarction. Spleen in the RLQ with chronic torsion and infarction is a very rare presentation for wandering spleen. In addition there is no report of such a presentation in a patient with AD-PCKD.

Recommendation

We recommend Clinicians to consider wandering spleen in their differential diagnosis in a patient presenting with RLQ abdominal mass and chronic abdominal pain.

Availability of supporting data

Data related with this case report is available at Addis ababa university, Tikur Ambesa Tertiary Hospital.

Abbreviations

Autosomal dominant polycystic kidney disease

Blood pressure

Low grade intermittent fever

High active anti-retroviral therapy

Right lower quadrant

Retro viral infection

Hypertension

White blood cell count

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Acknowledgements

We would like to thank the managing team of this patient including all the ward staffs who played a great role in the peri-operative management of this patient. We also appreciate the support of our consultants, residents and member of the department of surgery and HPB unit. Our kind gratitude goes to the family of this patient for their unreserved support in post-operative period that helped for the fast recovery of this patient

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Yitagesu aberra shibiru, Sahlu wondimu & Wassie almaw

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Dr. Yitagesu Aberra, Main author of this case report, is an HPB surgery fellow in the department of surgery, college of health science, Addis Ababa University who was the leading surgeon in the management of this patient. Dr. Sahlu Wendimu is an HPB surgery subspecialist and Assistant professor of General Surgery who was the consultant in duty during the management of this patient. Dr.Wassie Almaw is a 2nd year pediatric surgery resident attaching at HPB surgery unit who took part in the management of this patient.

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Ethical clearance is not applicable but we took oral and written consent from the patient for case presentation and publication.

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shibiru, Y.a., wondimu, S. & almaw, W. Wandering spleen presenting in the form of right sided pelvic mass and pain in a patient with AD-PCKD: a case report and review of the literature. J Med Case Reports 18 , 259 (2024). https://doi.org/10.1186/s13256-024-04580-6

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Accepted : 02 May 2024

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DOI : https://doi.org/10.1186/s13256-024-04580-6

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