Flexible sigmoidoscopy, a screening test for colorectal cancer that is less invasive and has fewer side effects than colonoscopy, is effective in reducing the rates of new cases and deaths due to colorectal cancer, according to research sponsored by the National Cancer Institute, part of the National Institutes of Health. In a study that spanned almost 20 years, researchers found that overall colorectal cancer mortality (deaths) was reduced by 26 percent and incidence (new cases) was reduced by 21 percent as a result of screening with sigmoidoscopy. These results appeared online, ahead of print, on May 21, 2012, in the New England Journal of Medicine, and were presented at Digestive Disease Week, a scientific conference.