Men's Health

Tools & Resources

This article is from the WebMD News Archive

Font Size

Sigmoidoscopy: How Often Is Enough?

Test for Colon Polyps Effective, Necessary Every 5 Years

By Jeanie Lerche Davis
WebMD Health News

April 15, 2003 -- Sigmoidoscopy -- a common test for colon cancer -- seems to keep cancer at bay for 16 years, maybe longer, a new study shows. But don't get too excited: Adults over 50 still need to get screened every five years, experts say.

In sigmoidoscopy, a doctor can examine the lower part of the colon, where most colon polyps develop. An alternative test, colonoscopy, involves looking at the entire colon and is advised every 10 years.

Getting sigmoidoscopic screenings every five years is important, experts have long said, because colon polyps can become cancerous. In fact, screenings can reduce the number of deaths from colorectal cancer.

But do people need the test quite so frequently?

In this new study, researchers analyzed information on sigmoidoscopy screening and risk factors for colorectal cancer on 1,668 people diagnosed with colon cancer and 1,294 who did not have cancer. Among those people who had sigmoidoscopy, there was an almost 75% reduction in colorectal cancer rates -- reductions that appeared to last for more than 16 years.

Their results are published in this month's Journal of the National Cancer Institute.

The findings from the study support the recommendation of a sigmoidoscopy (with colonoscopic follow-up) every 10 years to diagnose cancer polyps, writes lead researcher Polly A. Newcomb, PhD, with the Fred Hutchinson Cancer Research Center in Seattle.

However, this evidence is too premature to change the every-five-year recommendation, writes Jack S. Mandel, an epidemiologist with the Rollins School of Public Health at Emory University in Atlanta, in an accompanying editorial.

He calls for more studies looking at the issue of screening interval. "A more precise estimate of the benefit from sigmoidoscopy screening will have to await the results from the ongoing [randomized, controlled trials]," he writes. "At that time, we will be in a better position to more accurately evaluate the risks, benefits, and cost-effectiveness of screening. Those results will provide a better basis on which to develop screening policy."