Worldwide, colorectal cancer (CRC) is diagnosed in more than 1 million persons each year and more than 500 000 die of the disease. Colonoscopy, in which a flexible fiberoptic scope is used to inspect the colon and rectum and remove worrisome precancerous growths, is recommended for adults older than 50 years (or at younger ages for persons at increased risk for CRC). In highly standardized conditions, colonoscopy is associated with a reduction in the risk for CRC.