State variation in early-onset colorectal cancer in the United States, 1995-2015

: The extent to which the increase in early-onset colorectal cancer (CRC) in the United States varies geographically is unknown. We analyzed changes in CRC incidence and risk factors among people aged 20-49 years by state using high-quality population-based cancer registry data provided by the North American Association of Central Cancer Registries and national survey data, respectively. Early-onset CRC incidence was mostly stable among blacks and Hispanics but increased in 40 of 47 states among non-Hispanic whites, most prominently in western states. For example, rates increased in Washington from 6.7 (per 100 000) during 1995-1996 to 11.5 during 2014-2015 (rate ratio = 1.73, 95% confidence interval = 1.48 to 2.01) and in Colorado from 6.0 to 9.5 (rate ratio = 1.57, 95% confidence interval = 1.30 to 1.91). Nevertheless, current CRC incidence was highest in southern states. From 1995 to 2005, increases occurred in obesity prevalence in all states and heavy alcohol consumption in one-third of states, but neither were correlated with CRC incidence trends. Early-onset CRC is increasing most rapidly among whites in western states. Etiologic studies are needed to explore early life colorectal carcinogenesis.