HMOs Should Cover Full-Colon Exams, Researchers Say
Three studies presented this week -- two in major medical journals and the third at a medical conference -- show that even the most expensive screening test for colon cancer is more cost-effective than other widely accepted screening tests, such as mammography for breast cancer. The problem is that many people simply don't get tested, making colon cancer the second most common cause of cancer death in the U.S.
"Starting at age 50, people should undergo screening -- and if they do, they are very unlikely to get colon cancer," A. Lindsay Frazier, MD, tells WebMD. "The procedures [to choose from] are nearly identical in terms of outcome. The two things people should consider are annual fecal occult blood tests plus flexible sigmoidoscopy every five years, or colonoscopy every 10 years." Frazier, an oncologist at Boston's Dana-Farber Cancer Institute, is author of a study that used a mathematical model to compare all 22 colon cancer screening strategies now available.
Colon cancer starts with the formation of small, noncancerous growths called polyps. Over time, these polyps can gradually become larger, and some eventually become invasive cancers. Because this process takes about 10 years, there is lots of time to find and remove polyps before they become malignant.
Today, there are four ways to find polyps: by testing stool samples for traces of blood (with a fecal occult blood test or FOBT); by looking in the lower half of the colon with a flexible scope (sigmoidoscopy); by looking in the whole colon with a larger instrument that also can remove any polyps that are found (colonoscopy); or by giving a double-contrast barium enema, in which the patient swallows a substance that can be seen on X-ray, allowing the doctor to spot any abnormalities.
In the Dana-Farber study, the barium-enema method turned out to be the least effective strategy in terms of cost. This finding may well signal the end of the technique in the U.S. Screening with fecal occult blood test every year combined with flexible sigmoidoscopy every five years was the most cost-effective strategy. But colonoscopy every 10 years was nearly as good -- and even though the procedure is much more taxing than sigmoidoscopy, it eliminates the need for FOBT, which patients frequently fail to complete.
A second study by Amnon Sonnenberg, MD, and colleagues at the Veterans Affairs Medical Center in Albuquerque, N.M., found colonoscopy to be more cost-effective than either fecal occult blood test or sigmoidoscopy alone. Commenting on this study, University of Pennsylvania researcher James D. Lewis, MD, MSCE, suggests that colonoscopy is an attractive alternative for patients.