Risk of Colorectal Cancer and Colorectal Cancer Mortality Beginning Ten Years after a Negative Colonoscopy, among Screen-Eligible Adults 76 to 85 Years Old.

BACKGROUND: Few empirical data are available to inform older adults' decisions about whether to screen or continue screening for colorectal cancer based on their prior history of screening, particularly among individuals with a prior negative exam. METHODS: Using a retrospective cohort of older adults receiving healthcare at three Kaiser Permanente integrated healthcare systems in Northern California (KPNC), Southern California (KPSC), and Washington (KPWA), we estimated the cumulative risk of colorectal cancer incidence and mortality among older adults who had a negative colonoscopy 10 years earlier, accounting for death from other causes. RESULTS: Screen-eligible adults ages 76 to 85 years who had a negative colonoscopy 10 years earlier were found to be at a low risk of colorectal cancer diagnosis, with a cumulative incidence of 0.39% [95% CI, 0.31%-0.48%) at 2 years that increased to 1.29% (95% CI, 1.02%-1.61%) at 8 years. Cumulative mortality from colorectal cancer was 0.04% (95% CI, 0.02%-0.08%) at 2 years and 0.46% (95% CI, 0.30%-0.70%) at 8 years. CONCLUSIONS: These low estimates of cumulative colorectal cancer incidence and mortality occurred in the context of much higher risk of death from other causes. IMPACT: Knowledge of these results could bear on older adults' decision to undergo or not undergo further colorectal cancer screening, including choice of modality, should they decide to continue screening. See related commentary by Lieberman, p. 6.