Incidence trends of early-onset colorectal cancer (EOCRC) in the United States, by age, sex, race and ethnicity, and urbanicity (2000-2021).

26 Background: Research is needed to understand the extent to which the incidence of early onset colorectal cancer (EOCRC)is rising across population sub-groups, including by age, sex, race/ethnicity, and urbanicity, to inform hypotheses regarding its causes and strategies for screening and prevention. Methods: We used data on colorectal cancer cases diagnosed among adults 20-49 years (yr) between 2000-2021 in the delay-adjusted Surveillance, Epidemiology, and End Results (SEER) database (April 2024). We calculated delay- and age-adjusted annual incidence rates (IR) per 100,000, overall and by age, sex, race/ethnicity, and urbanicity. Urbanicity was defined using USDA Rural-Urban Continuum Codes for county; 1-3 were classified as urban and 4-9, 98, and 99 were classified as non-urban. We used NCI’s Joinpoint regression models (Joinpoint version 5.2.0.0) to estimate annual percent change (APC) and 95% confidence intervals (CI). We also calculated IRs for the most recent 5-year period (2017-2021) and used incidence rate ratios (IRR) to compare across groups; IRs and IRRs were calculated using SEER*Stat version 8.4.3. Results: Analyses included 155,500 cases of EOCRC. Most cases (72%) occurred among adults 40-49 yr; 22% occurred among those 30–39 yr and 6% in people 20-29 yr. Among adults 40-49 yr, the incidence of EOCRC increased 4.4% / yr on average between 2018-2021 (95%CI: 2.5, 5.6). Among adults 30-39 yr, incidence of EOCRC increased 3.0% / yr, on average, starting in 2010 (95%CI: 2.4, 4.5). For adults ages 20-29 yr, there were large increases in incidence from 2000-2016 (2000-2013, APC: 3.5; 95%CI: 2.4, 4.1; 2013-2016, APC: 11.2; 95%CI: 6.8, 13.5) but no change from 2016-2021. For the most recent 5-yr period (2017-2021), females had lower IR compared to males (IRR: 0.90; 95%CI: 0.88, 0.91), but trends over time were similar by sex. The incidence of EOCRC increased across races and ethnicities between 2000-2021, albeit at different rates. In the most recent period (2017-2021), the IR per 100,000 was 22.0 for Non-Hispanic American Indian and Alaskan Native (AIAN), 15.0 for Non-Hispanic White, 14.9 for Non-Hispanic Black, 12.4 for Hispanic or Latino, and 11.2 for Non-Hispanic Asian American or Pacific Islander adults. People in non-urban areas had a higher incidence of EOCRC compared to those in urban areas (IRR: 1.18; 95%CI: 1.14, 1.22), with similar trends over time. Conclusions: The incidence of EOCRC is highest among adults 40-49 yr, males, Non-Hispanic AIAN adults, and in non-urban areas. Trend analyses generally showed similar increases in incidence (3-5%/yr) in recent periods across sex, race/ethnicity, and urbanicity.