"High-risk patients aren't receiving timely follow-up colonoscopy but there is over-utilization among low-risk patients who are unlikely to develop colon cancer," Dr. Schoen said. "This misuse wastes health care resources and risks development of cancers in high-risk patients that might have been preventable." The second study, published in the January issue of GIE: Gastrointestinal Endoscopy, emphasizes a persistent, ongoing risk of cancer, despite colonoscopy, especially among patients with a history of advanced precancerous lesions.

For the study, 1,297 individuals who participated in the NCI's Polyp Prevention Trial, a four-year study which examined the effect of a low-fat, high-fiber, high-fruit and vegetable diet on precancerous polyp recurrence, were followed for an additional six years. Nine cases of colorectal cancer developed although the individuals had multiple colonoscopies during the 10-year observation period. Seven out of the nine subjects who developed cancer had a history of advanced precancerous lesions.

"Despite regular colonoscopy, colorectal cancer may still occur. This study emphasizes that patients with a history of advanced polyps are at particular risk and should be monitored closely with timely surveillance examinations," said Dr. Schoen. "Combined, these studies seriously indicate how surveillance colonoscopy is being implemented, and represent a call-to-action to align colonoscopy use with patient risk, especially in an era where we are trying to spend our health care dollars as effectively as possible."

Source: University of Pittsburgh Schools of the Health Sciences