Repeat Colonoscopies Underused in High-Risk Patients

ByABC News
May 20, 2008, 5:04 PM

May 21 -- TUESDAY, May 20 (HealthDay News) -- The people who most need to have repeat colonoscopies to detect precancerous growths are less likely to get the potentially lifesaving procedures, new research shows.

"We are doing more colonoscopies among the low-risk groups and not enough among the high-risk," study author Dr. Adeyinka Laiyemo, a cancer prevention research fellow at the National Cancer Institute, said during a press conference Monday at Digestive Disease Week 2008 in San Diego.

In a colonoscopy, a thin, lighted flexible tube with a tiny video camera is eased into the colon and a tiny camera transmits pictures to a TV screen. Small air puffs put into the colon keep it open and allow the doctor to see it clearly.

Laiyemo reported on the follow-up to the Polyp Prevention Trial, in which his team continued to follow those participants after the trial ended. The original trial was a four-year study in which some patients were randomly assigned to eat a low-fat, high-fiber diet with plenty of fruits and vegetables to see if it would prevent the recurrence of polyps, growths that can develop into colon cancers.

Of the 2,079 enrolled in the trial, 92 percent finished it, having an average of 3.1 colonoscopies, procedures that can detect colon cancer in early and curable stages. Of those, 1,297 patients agreed to be followed up by providing their subsequent colonoscopy reports.

During the six or more years of follow-up, 774 had repeat procedures. But while 30 percent of the patients termed low-risk (because they had a low risk of polyps at the end of the trial), just 41 percent of those classified as high risk of recurrence had repeat colonoscopies.

A second study, also presented at the conference, continues to support colonoscopy as the first line of detection for polyps. "The bigger the polyp, the greater the chance [the colon] has cancer already or it is going to turn into it," said Dr. Douglas Rex, a professor of medicine at Indiana University School of Medicine and director of endoscopy at Indiana University Hospital, in Indianapolis.