Colonoscopy with normal findings in patients with average risk of colorectal cancer was linked to decreased risk of colorectal cancer and associated mortality for more than 12 years, according to a study published in JAMA Internal Medicine.

A US-based group of researchers conducted a retrospective cohort study using an integrated health care delivery organization to analyze the long-term risks and deaths associated with colorectal cancer in patients who had negative colonoscopy results compared with patients who were unscreened. A total of 1,251,318 screening-eligible patients (49% men; average age, 55.6 years) who were at average risk were included in the study.  The main outcomes measured were colorectal cancer and associated deaths.

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Colonoscopy screenings were analyzed as a time-varying exposure in which all individuals included in the study contributed person-time unscreened until they were either screened or censored. If negative colonoscopy results were reported during the screening, individuals contributed person-time in the negative colonoscopy outcome group until they were censored.

Compared with unscreened patients, those who underwent colonoscopy at the current guideline-recommended rescreening interval had a 46% lower risk of colorectal cancer (HR, 0.54) and a 88% lower risk of colorectal cancer-associated deaths (HR, 0.12).  The investigators reported the reduced risk of colorectal cancer and colorectal cancer-associated mortality persisted for more than 12 years of follow-up for screened patients.

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“At the guideline-recommended 10-year rescreening interval after a negative colonoscopy result, risks of colorectal cancer and related deaths were 46% and 88% lower, respectively,” the authors wrote. “Our findings can inform guideline recommendations for rescreening and future studies to evaluate the costs and benefits of earlier vs later rescreening intervals.”


Lee JK, Jensen CD, Levin TR, et al. Long-term risk of colorectal cancer and related deaths after a colonoscopy with normal findings [published online December 17, 2018]. JAMA Intern Med. doi: 10.1001/jamainternmed.2018.5565