Long-Term Study Shows Fiber May Reduce Colon Cancer Risk

A diet high in grain fiber appears to inhibit the growth of rectal polyps, according to a four-year study of 58 patients reported Tuesday.

This finding could mean good news for people at risk of colorectal cancer, the second leading cause of deaths from cancer, said government scientists.

A team from Memorial Sloan-Kettering Cancer Center in New York and Cornell University Medical College selected study subjects from patients with familial adenomatous polyposis, an inherited disorder characterized by a large number of polyps in the colon that almost always will progress to cancer without treatment.

The patients had had the colon--the large bowel--removed.

Correlation Found

The report of the team appearing in the Journal of the National Cancer Institute used complex statistical techniques to show that “the ratio of rectal polyps to baseline was uniformly negatively correlated with high fiber”--that is, the higher the fiber, the fewer the polyps.

Members of the high fiber-group consumed an average of 22 grams of fiber a day, about twice what is contained in an average diet, through the inclusion of special cereals in their diet. Only about 10% of the population normally includes this much fiber.

Several studies have suggested that high-fiber, low-fat diets might protect against cancer of the rectum and the bowel. Studies that follow patients on a prescribed diet for a long period--four years for the NCI group--are rare, however.

Encouraging Results

“The results reported by these investigators are encouraging for the management not only of patients with familial adenomatous polyposis, but also others at risk of developing colorectal cancer, the second most frequent cause of cancer mortality in the Unite States,” said an editorial in the journal.

The researchers said it was not known whether the protective effect of grain fiber might also work in patients at risk for non-inherited polyps. “Enough correspondences exist between the two conditions to warrant active inquiry,” their report said.