Early Detection of Colorectal Cancer Following Changes to Screening Guidelines: A Population-Based Analysis of Adults Aged 45–49

Early Detection of Colorectal Cancer Following Changes to Screening Guidelines: A Population-Based Analysis of Adults Aged 45–49 | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Early Detection of Colorectal Cancer Following Changes to Screening Guidelines: A Population-Based Analysis of Adults Aged 45–49 Boniface Mensah, Albert E. Orhin, Greeshma Gaddipati, Natalie A. Y. Akoto, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6960721/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Introduction Colorectal cancer (CRC) is the third most common cancer worldwide, with millions of new cases and deaths annually. There has been an increasing incidence of CRC in patients less than 50 years, leading to recommendations for CRC screening initiation at age 45 in the United States by the American Cancer Society (ACS) in May 2018. However, it is unclear if CRC screening at ages 45-49 has increased detection of early-stage CRC (ES-CRC). Method We conducted a retrospective cohort study using Surveillance, Epidemiology, and End Results (SEER) database from 2015–2022, including individuals aged 45–49 diagnosed with CRC. The primary outcome was diagnosis of ES-CRC (in-situ or localized disease). The exposure was the time of diagnosis, categorized as pre-guideline (2015–2018) and post-guideline (2019–2022). Multivariable logistic regression assessed the association between time period and ES-CRC diagnosis, adjusting for demographic and socioeconomic factors. Subgroup analyses were conducted by sex, race, and marital status. Results Among 28,532 individuals, 13,413 (47.0%) were diagnosed pre-guideline and 15,119 (53.0%) post-guideline. The proportion of ES-CRC increased significantly post-guideline (31.1%) compared to pre-guideline update (29.8%, p-value = 0.012). Notably, a decline in ES-CRC diagnoses was observed in 2020, likely due to disruptions in cancer screening during the COVID-19 pandemic. The adjusted odds of ES-CRC diagnosis was higher post-guideline compared to pre-guideline update (AOR 1.068; 95% CI: 1.004–1.137). Subgroup analyses revealed higher odds of ES-CRC diagnosis among females, Asians and Black individuals post-guideline update. Conclusion Following the 2018 ACS guideline change, early-stage CRC diagnoses increased among adults aged 45–49. These findings suggest that the updated screening recommendations may have facilitated earlier detection in this age group. Figures Figure 1 Figure 2 Introduction Colorectal cancer (CRC) is one of the most common malignancies worldwide. It is the third most diagnosed cancer and the second leading cause of cancer death globally 1 . In 2020, roughly 1.9 million new CRC cases and 0.93 million deaths occurred worldwide, with incidence rates highest in high-income regions (e.g., Australia/New Zealand and Europe) 12 . Importantly, declines in CRC incidence have occurred in older adults in many affluent countries attributed to risk-factor changes (smoking, diet, etc.) and widespread screening 3 . However, a concerning divergence has emerged in younger populations as multiple reports document that CRC incidence among adults under 50 has been rising. For example, U.S. cancer registry data show that in 2019, 20% of CRC cases occurred in people aged ≤ 54 (up from 11% in 1995), and incidence in people aged 50 years and below grew by approximately 2% per year during the last decade 4 . Historically, most population screening guidelines recommended beginning average-risk CRC screening at age 50. However, the American Cancer Society (ACS) in 2018 lowered the recommended starting age to 45 years 5 .The U.S. Preventive Services Task Force (USPSTF) followed suit in 2021, expanding its age range to 45–75 years (Grade B for ages 45–49) 6 . The rationale was to detect cancer at an earlier, more curable stage as the stage at diagnosis strongly determines outcome. The 5-year relative survival is approximately 91.5% when detected in a localized stage versus only ~ 16.2% once distant metastases are present 7 . Randomized trials and observational studies have consistently shown that screening (via colonoscopy, FIT/FOBT, or sigmoidoscopy) reduces CRC mortality by shifting diagnoses toward earlier stages (by finding precancerous polyps or early tumors) 7 . Early evidence suggests this policy shift for earlier screening should increase screening uptake and earlier detection, but its real-world impact is still unclear 8 . We therefore aim to evaluate recent epidemiologic data for people aged 45 to 49-years to determine whether the rate of early-stage CRC detection (ES-CRC) in this age group has changed since the guideline update to start screening at age 45. This analysis will help assess whether lowering the screening age is translating into measurable improvements in early diagnosis among younger adults. Methods Study Design and Data Source We conducted a retrospective study using data from the Surveillance, Epidemiology, and End Results (SEER) database. The SEER database is a comprehensive source of population-based information on cancer incidence and survival in the United States. It covers approximately 48% of the U.S. population, containing patient demographics, characteristics of the tumor, and treatment received. Study Population The study included patients aged 45–49 who were diagnosed with colorectal cancer (CRC) between 2015 and 2022. The year 2019 was identified as an inflection point due to the update of the American Cancer Society (ACS) screening guidelines in 2018, which lowered the recommended age for CRC screening from 50 to 45 years. This allowed for a comparison of diagnoses of CRC before and after the guideline update. Variables and Measures The primary outcome of interest was diagnosis of early stage of CRC (ES-CRC). ES-CRC was defined as colorectal cancer in-situ and localized cancer (stage 1). The independent variable was the time period relative to the ACS guideline update with 2019 as the inflection point with pre-guideline period from 2015–2018 and post-guideline period from 2019–2022. We included multiple years before and after the inflection point to account for underlying trends, reduce short-term variability, and strengthen causal inference. Patient demographics including age at diagnosis, sex, marital status, race, median household income and urban rural continuum were obtained. Statistical Analysis Multivariable logistic regression analysis was used to evaluate the odds of diagnosis of ES-CRC in the specified age group before and after the guideline change adjusting for potential confounders such as sex, race, and other demographic factors. Subgroup analysis was also performed to determine the effect of the update on racial groups, sex and marital status. All analyses were performed using Stata version 18.5 (StataCorp). Data was analyzed in May 2025. A 2-sided P < 0.05 was considered statistically significant for all analyses. Result Study Population During the study period, a total of 28,532 individuals aged 45–49 were diagnosed with colorectal cancer (CRC) and included in the analysis. Of these, 13,413 individuals (47.0%) were diagnosed before the screening guidelines update, while 15,119 individuals (53.0%) were diagnosed after the update. Majority of the population were male, married, White population, had median household income of $ 60,000- $ 79,000 and lived in counties in metropolitan areas with more than 1 million population. Distribution of Early-Stage CRC Diagnoses Among the total CRC diagnoses, 8,695 cases (30.5%) were identified as early-stage colorectal cancer. There was a statistically significant increase in the proportion of ES-CRC diagnoses post-guideline update (4,705 cases, 31.1%) compared to the pre-update period (3,991 cases, 29.8%, p = 0.012), suggesting an improvement in early detection following the change in screening recommendations (Table 1 ). Notably, as illustrated in Fig. 1 , there was a decline in the proportion of ES-CRC diagnoses in 2020, likely influenced by the COVID-19 pandemic, which disrupted routine healthcare services, including cancer screening. Table 1 Baseline Characteristics of Study Population Pre-Screening Update (2015–2018) Post-Screening Update (2019–2022) p-value CRC Diagnosis N = 13,413 N = 15,119 Early-Stage CRC Diagnosis 3,991 (29.8%) 4,705 (31.1%) 0.012 Year of diagnosis 2015 3,281 (24.5%) < 0.001 2016 3,262 (24.3%) 2017 3,478 (25.9%) 2018 3,392 (25.3%) 2019 3,508 (23.2%) 2020 3,333 (22.0%) 2021 3,786 (25.0%) 2022 4,492 (29.7%) Sex Female 6,056 (45.2%) 6,924 (45.8%) 0.27 Male 7,357 (54.8%) 8,195 (54.2%) Marital Status Not married 3,674 (40.6%) 3,974 (38.7%) 0.007 Married 5,386 (59.4%) 6,306 (61.3%) Race White persons 7,464 (56.0%) 7,705 (51.6%) < 0.001 Black persons 1,831 (13.7%) 2,159 (14.5%) Hispanic persons 2,764 (20.7%) 3,477 (23.3%) Asian persons 1,149 (8.6%) 1,469 (9.8%) American Indian or Alaska Native persons 113 (0.8%) 108 (0.7%) Median Household Income <$40,000-$59,000 1,754 (13.1%) 1,625 (10.7%) 1 million population 8,734 (65.3%) 9,996 (66.2%) < 0.001 Counties in metropolitan areas with 250,000–1 million population. 2,265 (16.9%) 2,704 (17.9%) Counties in metropolitan areas with < 250,000 population 898 (6.7%) 963 (6.4%) Nonmetropolitan counties adjacent to a metropolitan area 955 (7.1%) 976 (6.5%) Nonmetropolitan counties not adjacent to a metropolitan area 530 (4.0%) 467 (3.1%) Statistical Analysis and Findings The adjusted odds ratio (AOR) for ES-CRC diagnosis post-guideline change was 6.8% higher compared to ES-CRC diagnosis pre-guideline update (AOR: 1.068 95% CI: 1.004–1.137, p-value = 0.038). Subgroup analysis showed that females (AOR:1.104, 95% CI: 1.009–1.208 p -value = 0.032), Asians (AOR:1.388, 95% CI:1.137–1.694 p-value = 0.001) and Black populations (AOR:1.241, 95% CI:1.051–1.466 p-value = 0.011) had significantly higher odds of ES-CRC diagnosis after the screening guidelines update as shown in Fig. 2 . Discussion In this retrospective study using SEER data, 28,532 individuals aged 45–49 diagnosed with CRC from 2015 to 2022 were analyzed. Following the ACS guideline change, the proportion of early-stage CRC diagnoses modestly but significantly increased from 29.8–31.1% (p = 0.012). Multivariable logistic regression confirmed a 6.8% higher adjusted odds of early-stage diagnosis post-guideline change. This modest improvement is in line with prior predictive modeling that suggested that lowering the screening age would lead to stage migration and increased early detection rates leading to increased survival 9 , 10 .However, national data show that CRC screening uptake remains low in this age group. According to the 2021 National Health Interview Survey, only about 20% of adults aged 45–49 years were up to date with CRC screening, the lowest rate among eligible age groups 4 . As awareness of the guideline increases and uptake improves over time, the impact of earlier screening on detection rates may become more pronounced. In the subgroup analysis, females demonstrated significantly greater odds of early-stage colorectal cancer (CRC) detection following the implementation of new screening guidelines (OR: 1.104, 95% CI: 1.009–1.208, p = 0.032), whereas the increase among males was not statistically significant. This sex-specific difference may be partly explained by variation in healthcare utilization and preventive care behavior. National CDC data indicate that, even excluding pregnancy-related visits, women are 33% more likely than men to routinely seek physician care, creating more frequent opportunities for screening and early detection 11 . Additionally, multivariable analysis from a study of Black Medicare beneficiaries in Baltimore found that men had 28% lower odds of being up to date with CRC screening compared to women (OR: 0.72, 95% CI: 0.52–0.99) 12 . These patterns point to a persistent behavioral and access gap that may contribute to earlier stage diagnosis in women and reinforce the need for targeted strategies to improve screening adherence among men. Similarly, Black individuals (AOR = 1.241, p = 0.011) were more likely to be diagnosed with early-stage CRC following the guideline change. This observation is consistent with previous literature showing that minority ethnic groups especially Black Americans bear a disproportionately high burden of CRC incidence and mortality 13 . However, studies also show that when equitable access to high-quality screening is provided, Black populations experience substantial benefits. For example, Alagoz et al. demonstrated that eliminating disparities in follow-up colonoscopy rates and endoscopist detection quality could reduce CRC incidence and mortality by 14.6% and 18.7%, respectively, and increase life-years gained by 7.1%, ultimately closing up to 59% of the CRC mortality gap between Black and White adults 14 .Although non-Hispanic Black adults have long been recognized as a high-risk group, with the American College of Gastroenterology recommending earlier screening starting at age 45 years as far back as 2005, these race-specific recommendations were inconsistently implemented and lacked broad support from payer reimbursement policies 15 . Consequently, this had a limited impact on population-level outcomes. Notably, our analysis compares time periods entirely after this 2005 recommendation, and the observed increase in early-stage CRC diagnoses among Black individuals became evident following the screening guideline update. This suggests that the standardized, universally endorsed screening guideline update likely played a more direct role in improving access and early detection in this population. Asian individuals also showed notably higher odds of early-stage CRC detection following the guideline change (AOR = 1.388, p = 0.001). While the underlying factors are not fully understood, this may reflect regional differences in healthcare access, screening uptake, or cultural attitudes toward preventive care. Further investigation is needed to explore these trends. Impact of COVID 19 on screening A notable dip in early-stage diagnoses in 2020 highlights the disruption caused by the COVID-19 pandemic, which significantly reduced access to preventive services 16 .Colonoscopy volumes reportedly dropped by more than 70% during the early months of the pandemic however there was a resurgence to pre pandemic levels after 17 . Limitations This study has limitations. First, its observational design limits the ability to draw causal conclusions, and the possibility of residual confounding from unmeasured factors such as family history, comorbidities, or access to care cannot be ruled out. Secondly, although the ACS guideline change occurred in 2018, real-world screening uptake may have been gradual. As such, some post-2019 diagnoses may still reflect cancers identified outside formal screening programs. Moreover, while the ACS recommended starting screening at age 45 in 2018, most insurers did not adopt this change until the USPSTF issued similar guidance in 2021. Because insurance coverage is typically aligned with USPSTF recommendations, early uptake in the 45–49 age group may have been limited, potentially underestimating the full effect of the guideline update during the study period. Conclusion Our study suggests that the American Cancer Society update to CRC screening guidelines, which lowered the recommended starting age to 45, may be contributing to a modest but meaningful increase in early-stage colorectal cancer diagnoses among U.S. adults aged 45–49. While the absolute gain is small, the trend aligns with expectations from modeling studies and highlights the potential value of earlier screening in improving outcomes. Notably, certain subgroups particularly women, Black individuals, and Asian individuals appear to have derived greater benefit, emphasizing the importance of equitable access and culturally informed outreach strategies. However, given the observational nature of the study and lack of screening-specific data, further prospective research is needed to confirm these patterns and better understand the mechanisms driving them. Continued efforts to monitor screening uptake, address disparities, and support timely follow-up remain essential to maximizing the impact of guideline changes on population health. Declarations Financial disclosure None to disclose Author Contribution B.M: conception, methodology, analysis, writing – original draft preparation, reviewing and editing. A.O: literature search, writing – original draft preparation. G.G: literature search, writing – reviewing and editing. N.A: literature search, writing – original draft preparation. S.H: writing– original draft preparation. R.B: writing – reviewing and editing. R.V: writing – reviewing and editing. J.A: writing – reviewing and editing. S.S: writing – reviewing and editing. P.K: supervision, writing- reviewing and editing. Data Availability Data used in this study can be accessed from the Surveillance, Epidemiology, and End Results Program database via the link https://seer.cancer.gov/data/ References Xi Y, Xu P. Global colorectal cancer burden in 2020 and projections to 2040. Transl Oncol . 2021;14(10):101174. doi:10.1016/j.tranon.2021.101174 Morgan E, Arnold M, Gini A, et al. Global burden of colorectal cancer in 2020 and 2040: incidence and mortality estimates from GLOBOCAN. Gut . 2023;72(2):338-344. doi:10.1136/gutjnl-2022-327736 Global Cancer Facts & Figures-5th Edition. Colorectal Cancer Facts & Figures 2023. Colorectal Cancer Screening Guidelines. Accessed June 5, 2025. https://www.cancer.org/health-care-professionals/american-cancer-society-prevention-early-detection-guidelines/colorectal-cancer-screening-guidelines.html US Preventive Services Task Force. Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement. JAMA . 2021;325(19):1965-1977. doi:10.1001/jama.2021.6238 Cancer of the Colon and Rectum - Cancer Stat Facts. SEER. Accessed June 5, 2025. https://seer.cancer.gov/statfacts/html/colorect.html Shafique N, Susman CG, Tortorello GN, Dheer A, Pettke E, Karakousis GC. Changing colon cancer screening guidelines to age 45: Has it made a difference? Surgery . 2024;176(3):680-683. doi:10.1016/j.surg.2024.06.003 Gupta S. Screening for colorectal cancer. Hematol Oncol Clin North Am . 2022;36(3):393-414. doi:10.1016/j.hoc.2022.02.001 Ladabaum U, Mannalithara A, Meester RGS, Gupta S, Schoen RE. Cost-Effectiveness and National Effects of Initiating Colorectal Cancer Screening for Average-Risk Persons at Age 45 Years Instead of 50 Years. Gastroenterology . 2019;157(1):137. doi:10.1053/j.gastro.2019.03.023 NCHS Pressroom - 2001 News Release - Women Visit Doctor More Often than Men. May 24, 2019. Accessed June 5, 2025. https://www.cdc.gov/nchs/pressroom/01news/newstudy.htm Martinez KA, Pollack CE, Phelan DF, et al. Gender differences in correlates of colorectal cancer screening among black Medicare beneficiaries in Baltimore. Cancer Epidemiol Biomark Prev Publ Am Assoc Cancer Res Cosponsored Am Soc Prev Oncol . 2013;22(6):1037-1042. doi:10.1158/1055-9965.EPI-12-1215 Augustus GJ, Ellis NA. Colorectal Cancer Disparity in African Americans. Am J Pathol . 2018;188(2):291-303. doi:10.1016/j.ajpath.2017.07.023 Alagoz O, May FP, Doubeni CA, et al. Impact of racial disparities in follow-up and quality of colonoscopy on colorectal cancer outcomes. JNCI J Natl Cancer Inst . 2024;116(11):1807-1816. doi:10.1093/jnci/djae140 Carethers JM. Commencing colorectal cancer screening at age 45 years in U.S. racial groups. Front Oncol . 2022;12:966998. doi:10.3389/fonc.2022.966998 Jackson SL. Preventive Service Usage and New Chronic Disease Diagnoses: Using PCORnet Data to Identify Emerging Trends, United States, 2018–2022. Prev Chronic Dis . 2024;21. doi:10.5888/pcd21.230415 Lee JK, Lam AY, Jensen CD, et al. Impact of the COVID-19 Pandemic on Fecal Immunochemical Testing, Colonoscopy Services, and Colorectal Neoplasia Detection in a Large United States Community-based Population. Gastroenterology . 2022;163(3):723-731.e6. doi:10.1053/j.gastro.2022.05.014 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6960721","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":479702021,"identity":"a0aa9ddd-c048-46cb-a366-dbc9acd6c7ea","order_by":0,"name":"Boniface Mensah","email":"data:image/png;base64,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","orcid":"","institution":"MedStar Union Memorial Hospital","correspondingAuthor":true,"prefix":"","firstName":"Boniface","middleName":"","lastName":"Mensah","suffix":""},{"id":479702022,"identity":"df23af47-2748-48dc-b779-a2b944bec8e3","order_by":1,"name":"Albert E. 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Y.","lastName":"Akoto","suffix":""},{"id":479702025,"identity":"5b2f9eee-9130-4391-a82d-a33e5d21a9f1","order_by":4,"name":"Seunghee Han MBChB","email":"","orcid":"","institution":"MedStar Union Memorial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Seunghee","middleName":"Han","lastName":"MBChB","suffix":""},{"id":479702026,"identity":"23c8d6e0-b2c3-499f-9fe0-fc2e51d427ca","order_by":5,"name":"Ramya Vasireddy","email":"","orcid":"","institution":"MedStar Union Memorial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ramya","middleName":"","lastName":"Vasireddy","suffix":""},{"id":479702027,"identity":"c6471885-bbe8-4ef6-b0be-b89ca7a71048","order_by":6,"name":"Rachel A. Boateng","email":"","orcid":"","institution":"Johns Hopkins University","correspondingAuthor":false,"prefix":"","firstName":"Rachel","middleName":"A.","lastName":"Boateng","suffix":""},{"id":479702028,"identity":"89289d19-03a4-455a-9d52-bfbd8faab82d","order_by":7,"name":"Joseph O. Atarere","email":"","orcid":"","institution":"MedStar Union Memorial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Joseph","middleName":"O.","lastName":"Atarere","suffix":""},{"id":479702029,"identity":"b394e891-92c0-4627-9000-b61d645e0f7d","order_by":8,"name":"Simardeep Singh","email":"","orcid":"","institution":"MedStar Union Memorial Hospital","correspondingAuthor":false,"prefix":"","firstName":"Simardeep","middleName":"","lastName":"Singh","suffix":""},{"id":479702030,"identity":"b2eaf76d-adc6-40d0-8a63-6413b81f44d9","order_by":9,"name":"Priyanka Kanth","email":"","orcid":"","institution":"MedStar Georgetown University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Priyanka","middleName":"","lastName":"Kanth","suffix":""}],"badges":[],"createdAt":"2025-06-24 02:38:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6960721/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6960721/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86139295,"identity":"f8473155-720b-4a0a-8c8f-49ffb26d03b7","added_by":"auto","created_at":"2025-07-07 08:14:33","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":213523,"visible":true,"origin":"","legend":"\u003cp\u003eProportion of Early CRC Diagnoses Per Year\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6960721/v1/429d36ed099ee96242b7d59d.jpeg"},{"id":86137930,"identity":"53fc0773-9cee-4023-98cd-e1431e9b6ad0","added_by":"auto","created_at":"2025-07-07 08:06:33","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":387805,"visible":true,"origin":"","legend":"\u003cp\u003eForest Plot of Adjusted Odd Ratios of ES-CRC diagnosis in Subgroup Populations\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6960721/v1/dcb68797a509cbc7b3fb0822.jpeg"},{"id":91255794,"identity":"2afe7a75-6638-4bf1-9847-154da9468799","added_by":"auto","created_at":"2025-09-13 20:46:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1420141,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6960721/v1/7451eafc-1b76-43d7-af56-bfc39652d546.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Early Detection of Colorectal Cancer Following Changes to Screening Guidelines: A Population-Based Analysis of Adults Aged 45–49","fulltext":[{"header":"Introduction","content":"\u003cp\u003eColorectal cancer (CRC) is one of the most common malignancies worldwide. It is the third most diagnosed cancer and the second leading cause of cancer death globally\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. In 2020, roughly 1.9\u0026nbsp;million new CRC cases and 0.93\u0026nbsp;million deaths occurred worldwide, with incidence rates highest in high-income regions (e.g., Australia/New Zealand and Europe)\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. Importantly, declines in CRC incidence have occurred in older adults in many affluent countries attributed to risk-factor changes (smoking, diet, etc.) and widespread screening\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. However, a concerning divergence has emerged in younger populations as multiple reports document that CRC incidence among adults under 50 has been rising. For example, U.S. cancer registry data show that in 2019, 20% of CRC cases occurred in people aged\u0026thinsp;\u0026le;\u0026thinsp;54 (up from 11% in 1995), and incidence in people aged 50 years and below grew by approximately 2% per year during the last decade\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e Historically, most population screening guidelines recommended beginning average-risk CRC screening at age 50. However, the American Cancer Society (ACS) in 2018 lowered the recommended starting age to 45 years\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.The U.S. Preventive Services Task Force (USPSTF) followed suit in 2021, expanding its age range to 45\u0026ndash;75 years (Grade B for ages 45\u0026ndash;49) \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. The rationale was to detect cancer at an earlier, more curable stage as the stage at diagnosis strongly determines outcome. The 5-year relative survival is approximately 91.5% when detected in a localized stage versus only\u0026thinsp;~\u0026thinsp;16.2% once distant metastases are present \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. Randomized trials and observational studies have consistently shown that screening (via colonoscopy, FIT/FOBT, or sigmoidoscopy) reduces CRC mortality by shifting diagnoses toward earlier stages (by finding precancerous polyps or early tumors)\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eEarly evidence suggests this policy shift for earlier screening should increase screening uptake and earlier detection, but its real-world impact is still unclear\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. We therefore aim to evaluate recent epidemiologic data for people aged 45 to 49-years to determine whether the rate of early-stage CRC detection (ES-CRC) in this age group has changed since the guideline update to start screening at age 45. This analysis will help assess whether lowering the screening age is translating into measurable improvements in early diagnosis among younger adults.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eStudy Design and Data Source\u003c/p\u003e \u003cp\u003eWe conducted a retrospective study using data from the Surveillance, Epidemiology, and End Results (SEER) database. The SEER database is a comprehensive source of population-based information on cancer incidence and survival in the United States. It covers approximately 48% of the U.S. population, containing patient demographics, characteristics of the tumor, and treatment received.\u003c/p\u003e \u003cp\u003eStudy Population\u003c/p\u003e \u003cp\u003eThe study included patients aged 45\u0026ndash;49 who were diagnosed with colorectal cancer (CRC) between 2015 and 2022. The year 2019 was identified as an inflection point due to the update of the American Cancer Society (ACS) screening guidelines in 2018, which lowered the recommended age for CRC screening from 50 to 45 years. This allowed for a comparison of diagnoses of CRC before and after the guideline update.\u003c/p\u003e \u003cp\u003eVariables and Measures\u003c/p\u003e \u003cp\u003eThe primary outcome of interest was diagnosis of early stage of CRC (ES-CRC). ES-CRC was defined as colorectal cancer in-situ and localized cancer (stage 1). The independent variable was the time period relative to the ACS guideline update with 2019 as the inflection point with pre-guideline period from 2015\u0026ndash;2018 and post-guideline period from 2019\u0026ndash;2022. We included multiple years before and after the inflection point to account for underlying trends, reduce short-term variability, and strengthen causal inference. Patient demographics including age at diagnosis, sex, marital status, race, median household income and urban rural continuum were obtained.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003e Multivariable logistic regression analysis was used to evaluate the odds of diagnosis of ES-CRC in the specified age group before and after the guideline change adjusting for potential confounders such as sex, race, and other demographic factors. Subgroup analysis was also performed to determine the effect of the update on racial groups, sex and marital status. All analyses were performed using Stata version 18.5 (StataCorp). Data was analyzed in May 2025. A 2-sided P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant for all analyses.\u003c/p\u003e \u003c/div\u003e"},{"header":"Result","content":"\u003cp\u003eStudy Population\u003c/p\u003e \u003cp\u003e During the study period, a total of 28,532 individuals aged 45\u0026ndash;49 were diagnosed with colorectal cancer (CRC) and included in the analysis. Of these, 13,413 individuals (47.0%) were diagnosed before the screening guidelines update, while 15,119 individuals (53.0%) were diagnosed after the update. Majority of the population were male, married, White population, had median household income of \u003cspan\u003e$\u003c/span\u003e60,000-\u003cspan\u003e$\u003c/span\u003e79,000 and lived in counties in metropolitan areas with more than 1\u0026nbsp;million population. \u003c/p\u003e \u003cp\u003eDistribution of Early-Stage CRC Diagnoses\u003c/p\u003e \u003cp\u003eAmong the total CRC diagnoses, 8,695 cases (30.5%) were identified as early-stage colorectal cancer. There was a statistically significant increase in the proportion of ES-CRC diagnoses post-guideline update (4,705 cases, 31.1%) compared to the pre-update period (3,991 cases, 29.8%, p\u0026thinsp;=\u0026thinsp;0.012), suggesting an improvement in early detection following the change in screening recommendations (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Notably, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, there was a decline in the proportion of ES-CRC diagnoses in 2020, likely influenced by the COVID-19 pandemic, which disrupted routine healthcare services, including cancer screening.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline Characteristics of Study Population\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePre-Screening Update (2015\u0026ndash;2018)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePost-Screening Update (2019\u0026ndash;2022)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCRC Diagnosis\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u0026thinsp;=\u0026thinsp;13,413\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u0026thinsp;=\u0026thinsp;15,119\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eEarly-Stage CRC Diagnosis\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,991 (29.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4,705 (31.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eYear of diagnosis\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2015\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,281 (24.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2016\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,262 (24.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2017\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,478 (25.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2018\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,392 (25.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2019\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3,508 (23.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2020\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3,333 (22.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2021\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3,786 (25.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2022\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4,492 (29.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFemale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6,056 (45.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6,924 (45.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7,357 (54.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8,195 (54.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMarital Status\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNot married\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,674 (40.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3,974 (38.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.007\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMarried\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5,386 (59.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6,306 (61.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRace\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWhite persons\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7,464 (56.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7,705 (51.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBlack persons\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1,831 (13.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2,159 (14.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHispanic persons\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2,764 (20.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3,477 (23.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAsian persons\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1,149 (8.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,469 (9.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAmerican Indian or Alaska Native persons\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e113 (0.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e108 (0.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian Household Income\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;$40,000-$59,000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1,754 (13.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,625 (10.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e$60,000-$79,000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5,351 (39.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4,381 (29.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e$80,000-$99,000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,253 (24.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5,010 (33.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e$100,000 and above\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,055 (22.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4,103 (27.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRural Urban Continuum\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCounties in metropolitan areas with \u0026gt;\u0026thinsp;1\u0026nbsp;million population\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8,734 (65.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9,996 (66.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCounties in metropolitan areas with 250,000\u0026ndash;1\u0026nbsp;million population.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2,265 (16.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2,704 (17.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCounties in metropolitan areas with \u0026lt;\u0026thinsp;250,000 population\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e898 (6.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e963 (6.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNonmetropolitan counties adjacent to a metropolitan area\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e955 (7.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e976 (6.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNonmetropolitan counties not adjacent to a metropolitan area\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e530 (4.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e467 (3.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eStatistical Analysis and Findings\u003c/p\u003e \u003cp\u003e The adjusted odds ratio (AOR) for ES-CRC diagnosis post-guideline change was 6.8% higher compared to ES-CRC diagnosis pre-guideline update (AOR: 1.068 95% CI: 1.004\u0026ndash;1.137, p-value\u0026thinsp;=\u0026thinsp;0.038). Subgroup analysis showed that females (AOR:1.104, 95% CI: 1.009\u0026ndash;1.208 p -value\u0026thinsp;=\u0026thinsp;0.032), Asians (AOR:1.388, 95% CI:1.137\u0026ndash;1.694 p-value\u0026thinsp;=\u0026thinsp;0.001) and Black populations (AOR:1.241, 95% CI:1.051\u0026ndash;1.466 p-value\u0026thinsp;=\u0026thinsp;0.011) had significantly higher odds of ES-CRC diagnosis after the screening guidelines update as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this retrospective study using SEER data, 28,532 individuals aged 45\u0026ndash;49 diagnosed with CRC from 2015 to 2022 were analyzed. Following the ACS guideline change, the proportion of early-stage CRC diagnoses modestly but significantly increased from 29.8\u0026ndash;31.1% (p\u0026thinsp;=\u0026thinsp;0.012). Multivariable logistic regression confirmed a 6.8% higher adjusted odds of early-stage diagnosis post-guideline change. This modest improvement is in line with prior predictive modeling that suggested that lowering the screening age would lead to stage migration and increased early detection rates leading to increased survival\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.However, national data show that CRC screening uptake remains low in this age group. According to the 2021 National Health Interview Survey, only about 20% of adults aged 45\u0026ndash;49 years were up to date with CRC screening, the lowest rate among eligible age groups\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. As awareness of the guideline increases and uptake improves over time, the impact of earlier screening on detection rates may become more pronounced.\u003c/p\u003e \u003cp\u003eIn the subgroup analysis, females demonstrated significantly greater odds of early-stage colorectal cancer (CRC) detection following the implementation of new screening guidelines (OR: 1.104, 95% CI: 1.009\u0026ndash;1.208, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032), whereas the increase among males was not statistically significant. This sex-specific difference may be partly explained by variation in healthcare utilization and preventive care behavior. National CDC data indicate that, even excluding pregnancy-related visits, women are 33% more likely than men to routinely seek physician care, creating more frequent opportunities for screening and early detection\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. Additionally, multivariable analysis from a study of Black Medicare beneficiaries in Baltimore found that men had 28% lower odds of being up to date with CRC screening compared to women (OR: 0.72, 95% CI: 0.52\u0026ndash;0.99)\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. These patterns point to a persistent behavioral and access gap that may contribute to earlier stage diagnosis in women and reinforce the need for targeted strategies to improve screening adherence among men. Similarly, Black individuals (AOR\u0026thinsp;=\u0026thinsp;1.241, p\u0026thinsp;=\u0026thinsp;0.011) were more likely to be diagnosed with early-stage CRC following the guideline change. This observation is consistent with previous literature showing that minority ethnic groups especially Black Americans bear a disproportionately high burden of CRC incidence and mortality\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. However, studies also show that when equitable access to high-quality screening is provided, Black populations experience substantial benefits. For example, Alagoz et al. demonstrated that eliminating disparities in follow-up colonoscopy rates and endoscopist detection quality could reduce CRC incidence and mortality by 14.6% and 18.7%, respectively, and increase life-years gained by 7.1%, ultimately closing up to 59% of the CRC mortality gap between Black and White adults\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e.Although non-Hispanic Black adults have long been recognized as a high-risk group, with the American College of Gastroenterology recommending earlier screening starting at age 45 years as far back as 2005, these race-specific recommendations were inconsistently implemented and lacked broad support from payer reimbursement policies\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Consequently, this had a limited impact on population-level outcomes. Notably, our analysis compares time periods entirely after this 2005 recommendation, and the observed increase in early-stage CRC diagnoses among Black individuals became evident following the screening guideline update. This suggests that the standardized, universally endorsed screening guideline update likely played a more direct role in improving access and early detection in this population.\u003c/p\u003e \u003cp\u003e Asian individuals also showed notably higher odds of early-stage CRC detection following the guideline change (AOR\u0026thinsp;=\u0026thinsp;1.388, p\u0026thinsp;=\u0026thinsp;0.001). While the underlying factors are not fully understood, this may reflect regional differences in healthcare access, screening uptake, or cultural attitudes toward preventive care. Further investigation is needed to explore these trends.\u003c/p\u003e \u003cp\u003eImpact of COVID 19 on screening\u003c/p\u003e \u003cp\u003eA notable dip in early-stage diagnoses in 2020 highlights the disruption caused by the COVID-19 pandemic, which significantly reduced access to preventive services\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e.Colonoscopy volumes reportedly dropped by more than 70% during the early months of the pandemic however there was a resurgence to pre pandemic levels after\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Limitations","content":"\u003cp\u003eThis study has limitations. First, its observational design limits the ability to draw causal conclusions, and the possibility of residual confounding from unmeasured factors such as family history, comorbidities, or access to care cannot be ruled out. Secondly, although the ACS guideline change occurred in 2018, real-world screening uptake may have been gradual. As such, some post-2019 diagnoses may still reflect cancers identified outside formal screening programs. Moreover, while the ACS recommended starting screening at age 45 in 2018, most insurers did not adopt this change until the USPSTF issued similar guidance in 2021. Because insurance coverage is typically aligned with USPSTF recommendations, early uptake in the 45\u0026ndash;49 age group may have been limited, potentially underestimating the full effect of the guideline update during the study period.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003e Our study suggests that the American Cancer Society update to CRC screening guidelines, which lowered the recommended starting age to 45, may be contributing to a modest but meaningful increase in early-stage colorectal cancer diagnoses among U.S. adults aged 45\u0026ndash;49. While the absolute gain is small, the trend aligns with expectations from modeling studies and highlights the potential value of earlier screening in improving outcomes. Notably, certain subgroups particularly women, Black individuals, and Asian individuals appear to have derived greater benefit, emphasizing the importance of equitable access and culturally informed outreach strategies. However, given the observational nature of the study and lack of screening-specific data, further prospective research is needed to confirm these patterns and better understand the mechanisms driving them. Continued efforts to monitor screening uptake, address disparities, and support timely follow-up remain essential to maximizing the impact of guideline changes on population health.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFinancial disclosure\u003c/h2\u003e \u003cp\u003eNone to disclose\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eB.M: conception, methodology, analysis, writing \u0026ndash; original draft preparation, reviewing and editing. A.O: literature search, writing \u0026ndash; original draft preparation. G.G: literature search, writing \u0026ndash; reviewing and editing. N.A: literature search, writing \u0026ndash; original draft preparation. S.H: writing\u0026ndash; original draft preparation. R.B: writing \u0026ndash; reviewing and editing. R.V: writing \u0026ndash; reviewing and editing. J.A: writing \u0026ndash; reviewing and editing. S.S: writing \u0026ndash; reviewing and editing. P.K: supervision, writing- reviewing and editing.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData used in this study can be accessed from the Surveillance, Epidemiology, and End Results Program database via the link https://seer.cancer.gov/data/\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eXi Y, Xu P. Global colorectal cancer burden in 2020 and projections to 2040. \u003cem\u003eTransl Oncol\u003c/em\u003e. 2021;14(10):101174. doi:10.1016/j.tranon.2021.101174\u003c/li\u003e\n\u003cli\u003eMorgan E, Arnold M, Gini A, et al. Global burden of colorectal cancer in 2020 and 2040: incidence and mortality estimates from GLOBOCAN. \u003cem\u003eGut\u003c/em\u003e. 2023;72(2):338-344. doi:10.1136/gutjnl-2022-327736\u003c/li\u003e\n\u003cli\u003eGlobal Cancer Facts \u0026amp; Figures-5th Edition.\u003c/li\u003e\n\u003cli\u003eColorectal Cancer Facts \u0026amp; Figures 2023.\u003c/li\u003e\n\u003cli\u003eColorectal Cancer Screening Guidelines. Accessed June 5, 2025. https://www.cancer.org/health-care-professionals/american-cancer-society-prevention-early-detection-guidelines/colorectal-cancer-screening-guidelines.html\u003c/li\u003e\n\u003cli\u003eUS Preventive Services Task Force. Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement. \u003cem\u003eJAMA\u003c/em\u003e. 2021;325(19):1965-1977. doi:10.1001/jama.2021.6238\u003c/li\u003e\n\u003cli\u003eCancer of the Colon and Rectum - Cancer Stat Facts. SEER. Accessed June 5, 2025. https://seer.cancer.gov/statfacts/html/colorect.html\u003c/li\u003e\n\u003cli\u003eShafique N, Susman CG, Tortorello GN, Dheer A, Pettke E, Karakousis GC. Changing colon cancer screening guidelines to age 45: Has it made a difference? \u003cem\u003eSurgery\u003c/em\u003e. 2024;176(3):680-683. doi:10.1016/j.surg.2024.06.003\u003c/li\u003e\n\u003cli\u003eGupta S. Screening for colorectal cancer. \u003cem\u003eHematol Oncol Clin North Am\u003c/em\u003e. 2022;36(3):393-414. doi:10.1016/j.hoc.2022.02.001\u003c/li\u003e\n\u003cli\u003eLadabaum U, Mannalithara A, Meester RGS, Gupta S, Schoen RE. Cost-Effectiveness and National Effects of Initiating Colorectal Cancer Screening for Average-Risk Persons at Age 45 Years Instead of 50 Years. \u003cem\u003eGastroenterology\u003c/em\u003e. 2019;157(1):137. doi:10.1053/j.gastro.2019.03.023\u003c/li\u003e\n\u003cli\u003eNCHS Pressroom - 2001 News Release - Women Visit Doctor More Often than Men. May 24, 2019. Accessed June 5, 2025. https://www.cdc.gov/nchs/pressroom/01news/newstudy.htm\u003c/li\u003e\n\u003cli\u003eMartinez KA, Pollack CE, Phelan DF, et al. Gender differences in correlates of colorectal cancer screening among black Medicare beneficiaries in Baltimore. \u003cem\u003eCancer Epidemiol Biomark Prev Publ Am Assoc Cancer Res Cosponsored Am Soc Prev Oncol\u003c/em\u003e. 2013;22(6):1037-1042. doi:10.1158/1055-9965.EPI-12-1215\u003c/li\u003e\n\u003cli\u003eAugustus GJ, Ellis NA. Colorectal Cancer Disparity in African Americans. \u003cem\u003eAm J Pathol\u003c/em\u003e. 2018;188(2):291-303. doi:10.1016/j.ajpath.2017.07.023\u003c/li\u003e\n\u003cli\u003eAlagoz O, May FP, Doubeni CA, et al. Impact of racial disparities in follow-up and quality of colonoscopy on colorectal cancer outcomes. \u003cem\u003eJNCI J Natl Cancer Inst\u003c/em\u003e. 2024;116(11):1807-1816. doi:10.1093/jnci/djae140\u003c/li\u003e\n\u003cli\u003eCarethers JM. Commencing colorectal cancer screening at age 45 years in U.S. racial groups. \u003cem\u003eFront Oncol\u003c/em\u003e. 2022;12:966998. doi:10.3389/fonc.2022.966998\u003c/li\u003e\n\u003cli\u003eJackson SL. Preventive Service Usage and New Chronic Disease Diagnoses: Using PCORnet Data to Identify Emerging Trends, United States, 2018\u0026ndash;2022. \u003cem\u003ePrev Chronic Dis\u003c/em\u003e. 2024;21. doi:10.5888/pcd21.230415\u003c/li\u003e\n\u003cli\u003eLee JK, Lam AY, Jensen CD, et al. Impact of the COVID-19 Pandemic on Fecal Immunochemical Testing, Colonoscopy Services, and Colorectal Neoplasia Detection in a Large United States Community-based Population. \u003cem\u003eGastroenterology\u003c/em\u003e. 2022;163(3):723-731.e6. doi:10.1053/j.gastro.2022.05.014\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6960721/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6960721/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eIntroduction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eColorectal cancer (CRC) is the third most common cancer worldwide, with millions of new cases and deaths annually. There has been an increasing incidence of CRC in patients less than 50 years, leading to recommendations for CRC screening initiation at age 45 in the United States by the American Cancer Society (ACS) in May 2018. However, it is unclear if CRC screening at ages 45-49 has increased detection of early-stage CRC (ES-CRC).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethod\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe conducted a retrospective cohort study using Surveillance, Epidemiology, and End Results (SEER) database from 2015–2022, including individuals aged 45–49 diagnosed with CRC. The primary outcome was diagnosis of ES-CRC (in-situ or localized disease). The exposure was the time of diagnosis, categorized as pre-guideline (2015–2018) and post-guideline (2019–2022). Multivariable logistic regression assessed the association between time period and ES-CRC diagnosis, adjusting for demographic and socioeconomic factors. Subgroup analyses were conducted by sex, race, and marital status.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAmong 28,532 individuals, 13,413 (47.0%) were diagnosed pre-guideline and 15,119 (53.0%) post-guideline. The proportion of ES-CRC increased significantly post-guideline (31.1%) compared to pre-guideline update (29.8%, p-value = 0.012). Notably, a decline in ES-CRC diagnoses was observed in 2020, likely due to disruptions in cancer screening during the COVID-19 pandemic. The adjusted odds of ES-CRC diagnosis was higher post-guideline compared to pre-guideline update (AOR 1.068; 95% CI: 1.004–1.137). Subgroup analyses revealed higher odds of ES-CRC diagnosis among females, Asians and Black individuals post-guideline update.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFollowing the 2018 ACS guideline change, early-stage CRC diagnoses increased among adults aged 45–49. These findings suggest that the updated screening recommendations may have facilitated earlier detection in this age group.\u003c/p\u003e","manuscriptTitle":"Early Detection of Colorectal Cancer Following Changes to Screening Guidelines: A Population-Based Analysis of Adults Aged 45–49","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-07 08:06:28","doi":"10.21203/rs.3.rs-6960721/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"21fffeb1-104f-4a50-b1fc-913b438ea08d","owner":[],"postedDate":"July 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-13T20:38:08+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-07 08:06:28","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6960721","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6960721","identity":"rs-6960721","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}