Abstract 3575: Early-onset colorectal and pancreatic cancer in the United States: Incidence and mortality projections through 2040

Abstract Background: Incidence of early-onset colorectal cancer (CRC) and pancreatic cancer (PC) has been rising in many high-income countries, including the United States, but medium-term projections for young adults remain limited. Health-care systems need age-specific forecasts to plan screening, prevention, and survivorship services for adults younger than 50 years. Methods: We used population-based U.S. incidence data for CRC and PC from 1999-2022 and mortality data from 1999-2023, aggregated into 13 five-year age groups (20-24 to 80-84 years). Age-period-cohort (APC) models were fitted with Poisson likelihoods using natural cubic splines for descriptive analyses and a Bayesian APC (BAPC) framework with integrated nested Laplace approximation (INLA) and second-order random-walk priors for projections to 2040. For each cancer and endpoint (incidence or mortality), age-specific posterior means and 95% credible intervals (CrIs) were obtained and then summed over ages 20-49 years to derive projected case counts and rates per 100,000 persons using U.S. population projections. Results: In 2020, the modeled incidence of CRC among adults aged 20-49 years was 12.9 cases per 100,000 persons (95% CrI, 12.3-13.5), corresponding to 16,854 cases (16,092-17,616), and is projected to increase to 21.6 (10.9-32.3) per 100,000 in 2030 and 52.2 (0-162) per 100,000 in 2040, or approximately fourfold higher than the 2020 mean estimate with very wide uncertainty. PC incidence in this age group was 2.08 (1.89-2.27) per 100,000 in 2020, corresponding to 2,707 cases (2,460-2,953), and is projected to rise to 2.83 (2.23-3.43) in 2030 and 4.98 (2.02-7.94) in 2040, roughly a 2.4-fold increase. In contrast, CRC mortality among adults aged 20-49 years is projected to increase more modestly, from 2.81 (2.64-2.97) deaths per 100,000 in 2020 to 3.25 (2.45-4.06) in 2030 and 3.41 (0.51-6.31) in 2040. PC mortality projections are highly uncertain: the mean rate decreases from 2.29 (2.11-2.47) per 100,000 in 2020 to 0.76 (0.33-1.19) in 2030 and 0.38 (0-1.08) in 2040, but CrIs include near-zero and values close to the 2020 baseline. Conclusions: Our APC modeling suggests that, if recent trends persist, early-onset CRC incidence in U.S. adults aged 20-49 years might increase substantially through 2040, with more moderate but still meaningful increases in PC incidence. Projected mortality trends are less pronounced for CRC and highly uncertain for PC, underscoring that these estimates should be interpreted as scenario-based projections rather than precise forecasts. These findings support intensified prevention and early-detection strategies in younger adults while highlighting the need to update projections as additional data accrue. Citation Format: Woo Joo Lee, Sumbal Aziz, Seon Hye Won, Muhammad Sohaib Asghar, Robin Park, Thomas Shimshak. Early-onset colorectal and pancreatic cancer in the United States: Incidence and mortality projections through 2040 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3575.