Effects of Organized Colorectal Cancer Screening on Cancer Incidence and Mortality in a Large Community-Based Population.

BACKGROUND & AIMS: Little information is available on the effectiveness of organized colorectal cancer (CRC) screening on screening uptake, incidence, and mortality in community-based populations. METHODS: We contrasted screening rates, age-adjusted annual CRC incidence, and incidence-based mortality rates before (baseline year 2000) and after (through 2015) implementation of organized screening outreach, from 2007 through 2008 (primarily annual fecal immunochemical testing and colonoscopy), in a large community-based population. Among screening-eligible individuals 51-75 years old, we calculated annual up-to-date status for cancer screening (by fecal test, sigmoidoscopy, or colonoscopy), CRC incidence, cancer stage distributions, and incidence-based mortality. RESULTS: Initiation of organized CRC screening significantly increased the up-to-date status of screening, from 38.9% in 2000 to 82.7% in 2015 (P < .01). Higher rates of screening were associated with a 25.5% reduction in annual CRC incidence between 2000 and 2015, from 95.8 to 71.4 cases/100,000 (P < .01), and a 52.4% reduction in cancer mortality, from 30.9 to 14.7 deaths/100,000 (P < .01). Increased screening was initially associated with increased CRC incidence, due largely to greater detection of early-stage cancers, followed by decreases in cancer incidence. Advanced-stage CRC incidence rates decreased 36.2%, from 45.9 to 29.3 cases/100,000 (P < .01), and early-stage CRC incidence rates decreased 14.5%, from 48.2 to 41.2 cases/100,000 (P < .04). CONCLUSIONS: Implementing an organized CRC screening program in a large community-based population rapidly increased screening participation to the ≥80% target set by national organizations. Screening rates were sustainable and associated with substantial decreases in CRC incidence and mortality within short time intervals, consistent with early detection and cancer prevention.