After nearly 12 years of follow-up, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial has shown that screening with flexible sigmoidoscopy reduces colorectal-cancer incidence by 21% and mortality by 26%. Colorectal cancer is the second leading cause of cancer-related deaths in the United States. 1 Colorectal-cancer mortality 2 – 4 and incidence 5 , 6 are reduced with screening by means of fecal occult-blood testing. Endoscopic screening with flexible sigmoidoscopy or colonoscopy is more sensitive than fecal testing for the detection of adenomatous polyps, the precursor lesions of colorectal cancer. 7 – 9 Three European randomized trials of flexible sigmoidoscopy have been performed. 10 In the United Kingdom, one-time screening with flexible sigmoidoscopy significantly reduced the incidence of colorectal cancer (by 23%) and associated mortality (by 31%). 11 In Italy, an 18% reduction in incidence and a nonsignificant 22% . . .