- The recommendation to begin colorectal cancer screening at ages 45 to 49 has increased participation rates in this younger age group.
- Earlier screening appears to have increased the earlier detection of asymptomatic cancers.
- A strategy involving mailing unsolicited FIT kits was more effective in increasing screening participation compared with three other screening strategies requiring active choice.
The proportion of younger adults undergoing colorectal cancer (CRC) screening has increased in the years after recommendations were first revised to include average-risk individuals ages 45 to 49, and this led to earlier detection of asymptomatic cancers in this age group, according to two studies.
In a study looking at screening participation trends using data from the National Health Interview Survey, CRC screening steadily increased among U.S. adults ages 45 to 49 after the American Cancer Society and U.S. Preventive Services Task Force (USPSTF) issued revised recommendations in 2018 and 2020, respectively, reported Jessica Star, MA, MPH, of the American Cancer Society, and colleagues in JAMA.
In a second study, also published as a research letter in JAMA, there was a steep increase in local-stage CRC incidence in adults ages 45 to 49 from 2019 to 2022, said Elizabeth J. Schafer, MPH, also of the American Cancer Society, and colleagues.
In addition, a randomized trial found that the most effective way to promote CRC screening in this younger group was to send unsolicited fecal immunochemical test (FIT) kits, reported Folasade P. May, MD, PhD, of the University of California Los Angeles, and colleagues.
The revised screening recommendations raised a number of questions, including whether expanding eligibility to younger adults would divert resources from and compromise progress made in screening older adults, whether lowering the screening age would affect population-level outcomes, and which strategies are needed to reach those individuals newly eligible for screening, wrote Caitlin C. Murphy, PhD, MPH, of the UTHealth Houston School of Public Health, and colleagues in an editorial accompanying the three studies.
The good news, the editorialists noted, is that despite some concerns about unintended consequences of earlier screening, the results from these studies "begin to answer these questions, and together, they provide encouraging signals that may assuage initial skepticism."
Increased Screening Participation
Among adults ages 45 to 49 years, the prevalence of up-to-date CRC screening increased from 20.8% in 2019 and 19.7% in 2021 to 33.7% in 2023, Star and team reported.
Colonoscopy prevalence increased from 19.5% in 2019 and 17.8% in 2021 to 27.7% in 2023, while stool-based testing increased from 1.3% and 2.7% to 7.1%, respectively.
The researchers also found that screening for adults ages 50 to 75 remained stable, "suggesting no reduced access for older individuals," they wrote.
Evidence of screening participation in the younger group of adults "is encouraging because screening reduces CRC mortality, mostly through the detection and removal of potentially precancerous lesions," Star and colleagues noted. However, they added that these increases were restricted to highly educated and insured individuals, "which may foreshadow widening disparities."
Of 18,645, 17,300, and 17,293 survey respondents ages 40 to 75 in 2019, 2021, and 2023, 14.8%, 13.9%, and 14% were ages 45 to 49. Most of these younger respondents were white and privately insured.
Colorectal Cancer Incidence
CRC incidence increased steadily by 1.6% annually since 2004 among adults ages 20 to 39 and by 2% to 2.6% annually since 2012 among adults ages 40 to 44 and 50 to 54, reported Schafer and team.
Notably, among those ages 45 to 49, an increase of 1.1% annually from 2004 to 2019 skyrocketed to 12% annually during 2019 to 2022.
This steep increase was driven by local-stage tumors (annual percentage change 21.8%, 95% CI 13.8-26.2), with an increase from 9.4 per 100,000 in 2019 to 11.7 per 100,000 in 2021 (a 25% relative increase), and then to 17.5 per 100,000 in 2022 (a 50% increase relative to 2021), after stable rates from 2004 to 2019.
Schafer and colleagues contrasted those substantial increases with consistent increases of distant-stage diagnoses observed in that age group, which "likely reflects diagnosis of prevalent asymptomatic cancer through first-time screening due to recommendations for adults to begin screening at age 45 years instead of 50 years."
For this study, Schafer and colleagues used data on CRC cases diagnosed from 2004 to 2022 among adults ages 20 to 54 that were obtained from 21 registries in the Surveillance, Epidemiology, and End Results (SEER) Program.
They identified a total of 219,373 cases of CRC (119,877 men, 99,496 women, mean age 46.9 years) during that period.
In their editorial, Murphy and colleagues noted that it isn't clear if the increased rates in the incidence of local-stage disease reflect slow-growing, indolent tumors, or if the detection of asymptomatic cancers will ultimately lead to decreased mortality.
"It will be important to monitor population-level outcomes as screening participation continues to increase among adults aged 45 to 49 years, as well as critical to determine the effect on mortality," they wrote.
Optimal Screening Strategy
In the randomized trial among adults ages 45 to 49, mailing an unsolicited FIT kit was more effective in increasing screening participation compared with three other CRC screening strategies requiring active choice through an electronic health record portal, May and team reported.
The single-center trial included 20,509 participants randomized to one of four outreach strategies: FIT-only active choice, colonoscopy-only active choice, dual-modality (FIT or colonoscopy) active choice, and usual care default mailed FIT outreach.
Screening participation was significantly lower in each of the three active-choice groups (FIT only: 16.4%; colonoscopy only: 14.5%; dual-modality FIT or colonoscopy: 17.4%) compared with the usual care default mailed FIT group (26.2%; all P<0.001).
The authors noted that, overall, screening rates were low, "underscoring the need for more effective strategies to engage this group."
The editorialists concluded that results from the studies suggested that "the critical next steps are to evaluate longer-term outcomes, especially mortality, and to ensure benefits are equally realized by scaling up implementation across diverse settings."
Disclosures
Schafer's study was supported by the Intramural Research Department of the American Cancer Society.
The randomized trial was funded by the UCLA Melvin and Bren Simon Gastroenterology Quality Improvement Program and a grant from the National Science Foundation Social Science Research Council.
Star and colleagues reported no conflicts of interest.
Schafer and colleagues reported no conflicts of interest.
May reported serving on the advisory board for Exact Sciences, Medtronic, and Geneoscopy.
Co-authors reported grants from the National Science Foundation, the NBER Roybal Center for Behavior Change in Health, and the USC Roybal Center for Behavioral Interventions in Aging.
Murphy reported consulting for Freenome and Universal Diagnostics. Co-authors reported no conflicts of interest.
Primary Source
JAMA
Source Reference: Star J, et al "Trends in colorectal cancer screening in US adults aged 45 to 49 years" JAMA 2025; DOI: 10.1001/jama.2025.10618.
Secondary Source
JAMA
Source Reference: Schafer EJ, et al "Colorectal cancer incidence in US adults after recommendations for earlier screening" JAMA 2025; DOI: 10.1001/jama.2025.9147.
Additional Source
JAMA
Source Reference: Galoosian A, et al "Population health colorectal cancer screening strategies in adults aged 45 to 49 years: a randomized clinical trial" JAMA 2025; DOI: 10.1001/jama.2025.12049.
Additional Source
JAMA
Source Reference: Murphy CC, et al “Younger adults, earlier screening — what we are learning about colorectal cancer and what comes next” JAMA 2025; DOI: 10.1001/jama.2025.11473.
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