The impact of rurality, socioeconomic status, and health literacy on lung cancer screening uptake: a systematic review protocol

Introduction

Lung cancer is the top cause of cancer-related deaths in the United States, resulting in nearly 124,730 deaths from lung cancer (64,190 in men and 60,540 in women) in 2024 (1). The U.S. Preventive Services Task Force (USPSTF) recommends low-dose computed tomography (LDCT) for individuals aged 50 to 80 who have a 20-pack-year smoking history and currently smoke or quit within the last 15 years (2). Although early detection through LDCT significantly improves survival, screening rates remain low nationwide, ranging from 1% to 16% (3). The 2021 USPSTF guideline update expanded eligibility, compared to the 2013 version, by lowering the screening age to 50 and reducing pack-years of smoking to 20 pack-years (2). As a result, the screening-eligible population grew from 8.15 million in 2013 to 13.5 million in 2022, a 65.9% increase (4).

Smoking, the primary risk factor for lung cancer, accounts for approximately 80% of lung cancer diagnoses (1). Smoking rates are disproportionately higher among individuals living in poverty (25.3% vs. 14.3%) (5), and education also plays a role. Individuals with a General Educational Development (GED) or less than a high school education have the highest smoking rates (61.8% and 41.4%, respectively) (6). In addition to smoking, other social determinants such as rurality, socioeconomic status (SES), and health literacy may also influence lung cancer risk and screening behaviors. Socioeconomic factors like income and insurance status can limit access to care and adherence to screening recommendations. Similarly, low health literacy may hinder individuals’ understanding of lung cancer risk, screening eligibility, and the importance of follow-up care, ultimately reducing participation in screening programs (7).

Rural communities often lack LDCT screening centers, face transportation barriers, and are underrepresented in national datasets, which makes it challenging to assess and address their needs effectively (8). Defined by the U.S. Census Bureau as areas with fewer than 2,500 residents or under 500 people per square mile (9), rural regions report higher smoking rates and mortality from lung cancer but are underrepresented in national screening data due to limited access and reporting gaps (8,10,11). A 2019 analysis identified poor rural inclusion in datasets like the Behavioral Risk Factor Surveillance System, which results in limited understanding of rural-urban differences in health behaviors (10). In Northern New England, a 2021 study found that even with more screening centers, rural areas still lacked adequate access, especially in places with high tobacco use, low education levels, and limited insurance options (11).

While prior research has examined rurality, SES, and health literacy independently, few studies have investigated how these factors interact to influence lung cancer screening rates (12). This comprehensive systemic review will evaluate how rurality, SES and health literacy individually and collectively impact lung cancer screening and early detection among U.S. adults aged 50–80 years. Figure 1 illustrates the intersection of these key factors. By reviewing studies published between 2014 and 2024, this work seeks to inform future research and guide policy strategies to address lung cancer screening disparities in rural communities.

Figure 1 Venn diagram demonstrating how rurality, low socioeconomic status, and limited health literacy can each create barriers to accessing screenings like LDCT and how overlapping factors may worsen access. For example, rural residents may face long travel distances, the uninsured may struggle with cost, and those with low health literacy may not understand screening importance. Combined, these factors greatly increase the risk of missed care opportunities and poor health outcomes. LDCT, low-dose computed tomography.

Methods

Study design

We will perform a comprehensive systematic review of existing literature to evaluate how rurality, SES, and health literacy impact lung cancer screening uptake. Given the limited availability of primary data on rural populations and a lack of previously published synthesis of relevant studies, a systematic review is necessary to synthesize existing evidence and highlight gaps in knowledge.

PROSPERO registration and PRISMA guidelines

The protocol was successfully approved and registered in PROSPERO before data extraction (Registration number: CRD42025644774).

To ensure a comprehensive and transparent review process, this systematic review will follow PRISMA guidelines (13), including use of the PRISMA flow diagram for quantitatively summarizing the search and inclusion exclusion processes (Figure 2).

Figure 2 Inclusion criteria flowchart.

Framework

We will leverage the Sample, Phenomenon of Interest, Design, Evaluation and Research (SPIDER) framework approach for a systematic literature review which is specifically designed for capturing complex, qualitative, or mixed-methods research questions (14). Unlike traditional frameworks which inform quantitative intervention studies, the flexibility of the SPIDER framework allows for the exploration of nuanced aspects of the research questions. SPIDER frames exploration of experiences, social determinants, and contextual influences, making it ideal for this study examining how factors like rurality (geographic distance, limited access to facilities, health infrastructure), SES (income, insurance coverage, and educational attainment), and health literacy (awareness, understanding, and education about lung cancer screening) affect lung cancer screening uptake. The research question is structured using the SPIDER framework as follows:

• S (sample): individuals residing in the U.S. meeting 2021 USPSTF guidelines for lung cancer screening.
• PI (phenomenon of interest): examination of the individual and intersectional effects of rurality, SES, and health literacy on lung cancer screening uptake.
• D (design): systematic literature review with defined inclusion and exclusion criteria.
• E (evaluation): assessment of the impact of rurality, SES and health literacy on lung cancer screening uptake. We will use a thematic approach to evaluate the impact of rurality, SES and health literacy by using themes like geographic access, limited health infrastructure, financial barriers and understanding of health risks. The primary outcome for this review, lung cancer screening uptake, is defined as the proportion of eligible individuals that undergo the screening test after being invited to do so (15).
• R (research type): systematic review to include randomized clinical trials, observational studies, case-control, cohort, cross-sectional, mixed-method research, qualitative and other systematic reviews; narrative reviews will be included only for their relevant context to support and strengthen background and discussion in this review.

Inclusion criteria

Figure 3 summarizes our inclusion criteria. We will include studies published between 2014 and 2024 to capture the most relevant and up-to-date evidence reflecting advancements in lung cancer screening guidelines and practices, including both the 2013 and 2021 USPSTF recommendations. While the USPSTF guidelines decreased the lower bound of eligibility age from 55 to 50 years in 2021, we chose this broader time frame to examine how the evidence evolved across both guideline periods. Eligible studies will adhere to the USPSTF guidelines for lung cancer screening (2). Studies must also focus on adults aged 50–80 years old living in the United States, as well as those comparing rural populations to urban or suburban populations. We will include studies that either focused exclusively on rural populations or compared rural populations to urban or suburban populations. This approach allows for a more comprehensive understanding of rural-specific challenges as well as rural-suburban/urban disparities in lung cancer screening uptake. The review will prioritize research addressing SES, including income, insurance coverage, educational attainment, and barriers related to rurality, such as geographic distance from healthcare services and limited access to healthcare infrastructure. Additionally, the review will investigate the role of health literacy factors, including awareness, understanding, and education about lung cancer risks and the importance of screening, and how these factors influence screening rates. Studies exploring the intersectionality between rurality, SES, and health literacy, including their combined effects on lung cancer screening rates and outcomes, will also be included. Research may examine these factors either within rural populations alone or through comparisons between rural and non-rural (urban or suburban) populations, with particular attention to the modifying or confounding effects of socioeconomic and health literacy factors on screening disparities. Only studies conducted in United States will be included.

Figure 3 PRISMA flowchart.

Exclusion criteria

Studies that are not in the English language or that did not meet the inclusion criteria will be excluded.

Information sources and search strategy

A preliminary search will be conducted to refine and validate search terms, ensuring they align with the research question. The search terms will be categorized into key concepts reflecting the focus of this study, including lung cancer, lung cancer screening, LDCT, socioeconomic factors, rurality, and health literacy. Table 1 illustrates the final search strategy developed for PubMed. A similar systematic search will be performed across additional selected databases (Web of Science, Embase) to ensure comprehensive retrieval, utilizing Boolean operators, subject headings, and keywords for precision and depth. The entire search process will be meticulously documented, including details of the databases searched, the exact search terms used, and the number of results retrieved from each source. This documentation will ensure reproducibility and transparency in the search strategy throughout the review.

Abstract and full-text review, data extraction

To avoid delays in the review process and allow time for Covidence training, an online tool that supports systematic reviews by managing screening, full-text review, and data extraction, we will begin by importing the PubMed search results into an Excel sheet for an initial screening of titles and abstracts. Two independent reviewers will evaluate these records against the inclusion and exclusion criteria, classifying each article as “yes”, “no”, or “cannot tell” based on its relevance to the research question. Only articles coded as “yes” or “cannot tell” will proceed to the next stage of screening.

Records from Embase and Web of Science will be imported directly into Covidence, where duplicates will be automatically identified and removed prior to screening.

For the full-text review and data extraction phase, all eligible studies, including those initially screened in Excel (PubMed) and those screened in Covidence (Embase & Web of Science), will be imported into Covidence for further assessment. At this stage, additional duplicates may be identified and removed before full-text review begins. Once duplicates are removed, the remaining eligible records will undergo a thorough full-text analysis, followed by detailed data extraction to ensure comprehensive and accurate inclusion of relevant studies.

Data extraction will be conducted independently by two reviewers. Any discrepancies that arise will be resolved through discussion and mutual agreement based on the inclusion and exclusion criteria of the review. If consensus cannot be reached, a third reviewer will be consulted to provide an unbiased opinion and facilitate resolution.

Critical appraisal of individual sources of evidence

Additionally, independent reviewers will assess potential biases in the included studies using the Risk of Bias in Non-randomized Studies of Exposures tool (ROBINS-E) (16) for observational studies and Covidence Quality Assessment Template will be used for clinical trial studies. This structured approach ensures consistency in appraising the quality of evidence and resolving conflicts related to bias assessments. All decisions and resolutions will be documented to maintain transparency and reproducibility.

Dealing with missing data

In cases where data are unavailable, two reviewers will attempt to contact the original authors via email or request supplementary information through the Vanderbilt University library. If the data remains unattainable, the study will be excluded from the analysis. This will be acknowledged as one of the limitations of the study.

Discussion

Through this systematic review, we aim to underscore the importance of understanding the complexities surrounding the intersectionality of rurality, SES, and health literacy on lung cancer screening uptake and to advocate for more targeted research in this area to inform effective interventions. Our goal is to provide evidence-based insights that can guide strategies to improve access to lung cancer screening, enhance adherence, and ultimately improve survival rates in rural populations across the United States. The impact of lung cancer screening on lung cancer outcomes is highly dependent on screening uptake rates, making it essential to identify strategies that improve screening uptake. Understanding factors that influence screening uptake rates can help improve lung cancer screening among eligible populations and assist policymakers in selecting approaches that align with the socio-cultural context in which they are implemented (17).

This systematic review will address critical gaps in understanding the intersectionality of rurality, SES, and health literacy on lung cancer screening uptake. Using a robust tiered, framework-based approach formulated by the A.P. et al. systematic review team, this review will synthesize evidence from multiple studies to explore how these key variables interact to influence screening. The findings will influence future multifaceted approaches to addressing barriers to lung cancer screening, particularly in rural populations. The combination of access limitations, financial constraints, and health literacy may compound barriers to care rural populations face. The evidence generated through this review will fill existing gaps in the literature and provide a foundation for policymakers to design targeted, data-driven interventions to improve lung cancer screening uptake in rural areas, ultimately advancing cancer care for rural populations.

Acknowledgments

None.

Footnote

Peer Review File: Available at https://tlcr.amegroups.com/article/view/10.21037/tlcr-2025-599/prf

Funding: This study was supported by the Veterans Affairs (VA) Tennessee Valley Healthcare System, Nashville TN (resources with use of facilities to L.B.S. and J.A.L.). The study was also supported in part by a LUNGevity Foundation VA Research Scholars Award (2021-08 to J.A.L.), National Cancer Institute, Vanderbilt-Ingram Cancer Center Support Grant (No. CA68485 to L.B.S. and J.A.L.), VA Merit 1 I01 CX002686-01 (to J.A.L.), the VETWISE-LHS Center of Innovation Tennessee Valley Healthcare System (CIN 24-128) - Veterans Health Administration, Nashville, TN, USA (to L.B.S. and J.A.L.), the Bristol Myers Squibb Foundation (to J.A.L. and L.B.S.), and the National Center for Advancing Translational Sciences UL1 TR002243 (to R.N.J.).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tlcr.amegroups.com/article/view/10.21037/tlcr-2025-599/coif). A.K. reports financial supports from American Cancer Society, MPH Fellowship. R.N.J. reports the effort on this study was supported by a grant from the National Center for Advancing Translational Sciences (NCATS). J.A.L. reports resources and use of facilities from VA Tennessee Valley Healthcare System, VA Research Scholars Award (grant funding) from LUNGevity Foundation, Vanderbilt Ingram Cancer Center Cancer Center Support Grant (funding) from National Cancer Institute, Merit (grant funding) and COIN (funding) from VA Office of Research and Development, funding from Bristol Myers Squibb Foundation, support for traveling to annual conference from Bristol Myers Squibb Foundation and Rescue Lung Society, serve as Treasurer of the Rescue Lung Rescue Life Society, serve on the Pre-Screening Committee of VA Lung Precision Oncology Program, serve on the National Lung Cancer Roundtable’s Provider Engagement and Outreach Task Group of American Cancer Society, and as a medical co-director of research for the VA TVHS Lung Cancer Screening Program of VA Tennessee Valley Healthcare System. L.B.S. reports resources and use of facilities from VA Tennessee Valley Healthcare System, Vanderbilt Ingram Cancer Center Cancer Center Support Grant (funding) from National Cancer Institute, COIN (funding) from VA Office of Research and Development, funding from Bristol Myers Squibb Foundation, CDC, State of TN and NIH, honoraria for Grand Rounds lectures at academic medical centers, support for traveling to annual conference from Bristol Myers Squibb Foundation and American Cancer Society Roundtable, and serve as a Chair (by-Laws Committee) of Association of Academic Radiologists (AAR). The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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