There is insufficient evidence to support the inclusion or exclusion of fecal occult blood testing or sigmoidoscopic or colonoscopic screening of asymptomatic patients over 40 years of age.
There is fair evidence to support screening with colonoscopy of patients in kindreds with the cancer family syndrome and patients with ulcerative colitis.
Randomized controlled trials are needed to determine the benefit of screening with sigmoidoscopy. Development of better risk stratification for screening if a high research priority.