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

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.