All 22 were deemed to extend life expectancy, but the most effective was annual testing for blood in the stool plus sigmoidoscopy every five years from age 50 to 85. Overall, the cost-effectiveness of most of the methods compared favorably with screening for other cancers, such as the annual Pap test used to detect cervical cancer and yearly mammograms for women ages 55 to 64. The American Cancer Society estimates that 130,000 cases of cancer of the colon or rectum will be diagnosed this year, with about 47,000 deaths.
Lung cancer is the only form of cancer that kills more people.
Sigmoidoscopy uses a flexible tube inserted through the rectum into the large intestine to detect polyps or cancerous tumors. It is less costly but also less thorough than a colonoscopy, a similar method that generally is used on high-risk patients and goes deeper into the colon.