Colonoscopy Outperforms Sigmoidoscopy for Cancer Screening

The contention that colonoscopy prevents right-sided colorectal cancer is now supported by numerous lines of evidence, although colonoscopy has not been evaluated in randomized, controlled trials.

In the current retrospective cohort study, investigators compared the risk for colorectal cancer in 42,938 patients with negative colonoscopy and 93,359 patients with negative sigmoidoscopy. All examinations were performed for screening.

During 553,543 person-years of follow-up, 241 cases of colorectal cancer were detected. The risk for colorectal cancer after negative screening colonoscopy was 58% lower overall — and 70% lower for proximal colorectal cancer — compared with the risk after negative screening sigmoidoscopy. The risk for distal cancer …