Colon Test Can Be Done Less Frequently

SEATTLE (Ivanhoe Newswire) -- Doctors may be asking people to undergo a common test used to screen people for colon cancer much too frequently, finds a new study.

Researchers reviewing data on the test known as screening sigmoidoscopy find the test is effective in reducing the incidence of colorectal cancers for as long as 16 years. Current recommendations call for people to have the test once every five years.

Sigmoidoscopy is similar to a colonoscopy, but, instead of examining the entire colon and rectum for precancerous polyps, it examines only the lower part of the colon, where more than 60 percent of all colorectal cancers are found. Studies show the test is effective in reducing the death rate from colon cancer. Scientists also believe it cuts down on the incidence of the cancer, because polyps found during the test can be removed before they cause problems.

Less certain, however, has been how often someone should have the test. Past studies have suggested it takes up to 15 years for polyps to develop into cancer. These researchers aimed to get a more accurate statistic by studying 1,668 colon cancer patients and 1,294 healthy people. All were assessed for colorectal risk factors and use of the sigmoidoscopy test to identify precancerous polyps.

The investigators found a significant reduction in the incidence of colon cancers in the individuals who had undergone the test. Overall, this group had a four-fold reduction in the incidence of the cancer, and those reductions were sustained over more than 15 years.

The researchers hope these findings will help determine how often the test should be performed. They also hope they will encourage more people to take the test in the first place, noting just 34 percent of adults age 50 and older have had either a sigmoidoscopy or a colonoscopy within the past five years.

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