Using colonoscopy to examine the entire colon's lining in 3,121 apparently healthy people aged 50-75, researchers found that 10 percent had colon cancer or serious precancerous growths. Dr. Lieberman and his colleagues conducted the research at 13 VA medical centers around the country. The VA study is the first to directly compare exams limited to the distal colon with exams of the entire colon to determine possible additional benefits of colonoscopy screening in an asymptomatic group of patients. The most striking finding was that one-third of all patients with serious lesions would not have been detected with sigmoidoscopy. Colonoscopy also appeared to be reasonably safe, the team found, with few complications such as bleeding or reactions to sedation used to make patients more comfortable during the procedure.
Colorectal cancer is the second leading cause of cancer deaths in North America.
In the U.S. alone, an estimated 138,000 men and women will be diagnosed with colorectal cancer this year, and about 55,000 will die from the disease. This particular kind of cancer is marked by a premalignant phase, growths called polyps in the colon lining. Not all polyps are destined to become cancerous, Dr. Lieberman noted, but those that progress to cancer typically develop abnormalities along the way that flag them as dangerous. This gives us a unique opportunity. If we can find the serious polyps and remove them, we can prevent colon cancer.