The world of cancer screening has been rocked recently by controversy. Long-standing recommendations on screening for breast, cervical, and prostate cancer have all been questioned based on either new data or reanalyses of older data. A similar controversy is also emerging for colorectal cancer screening.
In the 1980s, sigmoidoscopy screening was common despite lack of evidence for its efficacy. In ensuing decades, case-control studies established that sigmoidoscopy was associated with reduced incidence and mortality from left-sided but not right-sided colon malignancies.1,2 The results of a randomized trial of sigmoidoscopy screening reported by Atkin et al3 established the efficacy of sigmoidoscopy in reducing mortality due to colorectal cancer. As in the case-control studies, the randomized trial found that this effect was limited to the distal colon.