Colorectal Cancer :: Diet, lifestyle affect colorectal adenoma recurrence

Experts agree that people who have had three or more potentially precancerous adenomatous polyps removed during a colonoscopy should be “rescoped” in three years to make sure the polyps do not recur.

But now researchers at the National Cancer Institute (NCI) have identified other factors that independently raise the risk of recurrence.

Two of these risk factors – being over 65 years old, and male – cannot be modified, but the third ? obesity ? can, say the researchers.

The results can further help physicians stratify patients at greatest need for follow-up colonoscopies, they say, and can also inform patients about their own risk.

“In a situation where there are not enough physicians, or where doctors have long waiting lists for those who are not first-timers to a colon cancer check-up, then this risk stratification may help physicians prioritize which patients should be seen first,” said Adeyinka Laiyemo, M.D., a cancer prevention fellow at NCI.

For patients, Dr. Laiyemo says that “it is important to follow your doctor?s recommendation based on the nature of polyp removed during colonoscopy, and maintain a healthy weight. However, men should also recognize that they may be at a higher risk for developing worrisome polyps, and so should women who are over 65 years of age.”

The researchers say the findings support the 2006 consensus guidelines, developed jointly by the U.S. Multi-Society Task Force on Colorectal Cancer and the American Cancer Society. These guidelines recommend that people with an advanced adenoma or three or more adenomatous polyps should undergo repeat colonoscopy in three years. The issue, according to the group, is that many patients were being rescoped earlier than recommended, and that these repeat colonoscopies constituted a significant portion of endoscopic practices, draining resources away from patients in need of first time screenings. Previous studies have found that a three-year interval was just as safe for people with three or more adenomatous polyps, high-grade dysplasia, or an adenoma one centimeter or larger in diameter.

This study was designed to see if these guidelines adequately identified patients who later developed dangerous polyps, and also sought to discover other factors associated with increased risk. The research team used data from participants in the Polyp Prevention Trial (PPT), which assessed the impact of a low-fat, high-fiber, high fruits and vegetables diet on polyp recurrence. They examined the diet, lifestyle, and polyp characteristics in 1,905 participants at baseline, after they had a colonoscopy in which at least one polyp was removed and before they altered their eating habits to conform to PPT rules.

Within four years, 230 PPT participants developed high-risk polyps, and 524 had a low-risk adenoma recurrence. Dr. Laiyemo and his team found that, indeed, the presence of multiple adenomas was the largest risk factor associated with polyp recurrence, but that age, gender and obesity played important, if lesser, roles in stratifying risk. Of these factors, age was the most statistically significant, followed by gender and then obesity, he reports.

The only statistically significant factor they found that lowered risk was use of non-steroidal anti-inflammatory drugs (NSAIDs).

“We know from previous studies that NSAIDs can reduce polyp formation, but perhaps at a cost, due to some side effects that have been observed,” Dr. Laiyemo said. “We think that people should follow the consensus guidelines, but these other variables should also be considered when judging an individual?s risk and the need for follow-up colonoscopies at the appropriate time.”

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