Background: The incidence of colorectal cancer in the United States declined substantially over the past 20 years, but evidence suggests that among younger adults (under 50 years at diagnosis), incidence is increasing. However, data on age- and stage-specific incidence trends across racial/ethnic groups are limited.Methods: All incident cases of colorectal cancer diagnosed from 1990 through 2014 in adults aged 20 years and older were obtained from the California Cancer Registry. Incidence rates (per 100,000), incidence rate ratios, and triannual percent changes in incidence were estimated for each age group at diagnosis (20-49, 50-74, 75+ years), sex, stage, and race/ethnicity (non-Hispanic white, non-Hispanic black, Hispanic, and 7 Asian American groups).Results: Of 349,176 incident colorectal cancer cases diagnosed from 1990 through 2014, 9% were in adults younger than 50 years. Increases in incidence of early-onset colorectal cancer, especially in regional/distant stage disease, were observed in most racial/ethnic groups (statistically significant for non-Hispanic whites and Hispanics, ranging from 0.9% to 2.9% every 3 years). Incidence also increased in Vietnamese and other Southeast Asian groups of screening age (50-74 years). The incidence of colorectal cancer in non-Hispanic blacks aged 50+ declined over the 25-year period, but remained significantly higher than in non-Hispanic whites.Conclusions: Further research is needed to understand the causes of the increasing incidence of early-onset colorectal cancer. The rising incidence of colorectal cancer among Southeast Asians of screening age and the persistently high incidence in non-Hispanic blacks also warrant attention.Impact: Our findings may have implications for revisiting screening guidelines in the United States. Cancer Epidemiol Biomarkers Prev; 27(9); 1011-8. ©2018 AACR.
©2018 American Association for Cancer Research.