A study published online today by the New England Journal of Medicine finds that flexible sigmoidoscopy can cut the risk of developing colon cancer or dying of the disease even though the test only scans about the lower third of the colon.
The more costly colonoscopy covers the entire large intestine and is preferred by many doctors, but patients often balk at the higher cost and the fact that it requires both anesthesia and a regimen of drinking a laxative solution to cleanse the bowel the day before. Sigmoidoscopy can cost between $150 and $300; colonoscopy costs $1,000 to $2,000.
The U.S. study involved 154,900 men and women ages 55 to 74, with gastroenterologist Robert E. Schoen of the University of Pittsburgh medical school, as lead author. Participants were randomly assigned to sigmoidoscopy, with colonoscopy followup if needed, or to "usual care," with screenings only performed if ordered by the patients' regular physicians.
The results support the use of the sigmoidoscopy, in which polyps can be removed without anesthesia in a regular doctor's office. When left in place, polyps can become malignant.
In the study, if polyps were found, a colonoscopy was then performed and the tissue removed.
Part of the National Cancer Institute's Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, the study showed that such screenings resulted in a 21 percent reduction in cancer incidence overall and a 50 percent decline in death due to cancer in the left colon, the portion closest to the rectum examined in sigmoidoscopy.
"The two real important points [of the study] are the prevention of getting the disease and dying of the disease," Dr. Schoen said.
"When we are doing colorectal screenings, we are looking for the precursor of cancer, the polyp. We did a sigmoidoscopy, where we looked inside and saw the polyps."
Preventing cancer is preferable to treating the disease, Dr. Schoen said, explaining the importance of colorectal screenings, which differ from PSA tests for prostate cancer and mammograms for breast cancer.
"It's better than early detection."
Pohla Smith: email@example.com or 412-263-1228. First Published May 21, 2012 11:15 AM