Source: Hong Kong Med J  |  Posted 6 years ago

By Ed Susman

ANAHEIM, CA -- April 21, 2005 -- People at high risk of colon cancer appear to reduce the risk of developing polyps while taking calcium supplements and continue to benefit for as long as 5 years after they stop taking them, researchers said at the 96[^]th[] annual meeting of the American Association for Cancer Research.

"This provides further evidence of the potential of calcium to be used as a chemopreventive agent against development of colorectal cancer," said Elizabeth Barry, PhD, professor of epidemiology, Dartmouth Medical School, Hanover, New Hampshire, United States.

Co-author, John Baron, MD, professor of medicine, Dartmouth Medical School, said participants who were randomized to take 1200 mg of elemental calcium daily for 4 years had a "statistically significant 19% reduction in polyp formation" compared to placebo at the conclusion of the study.

Dr. Barry and Dr. Baron discuss the findings of their study here on April 20[^]th[] at the American Association for Cancer Research.

The cohort of 822 patients was followed another 5 years after the end of the study, and the researchers found that "the patients randomized to calcium achieved a 36% reduction in new adenoma polyp formation," Dr. Baron said. He said, however, that this added benefit, "did not persist beyond 5 years."

He also noted that calcium supplementation did not appear to be of much help for patients with advanced adenoma formation.

"I'm a fan of calcium supplementation," Dr. Baron said at his poster presentation, but he held short of making a general recommendation about calcium supplementation use to prevent colon cancer.

"I do believe that calcium supplementation reduces the risk of cancer, especially colon cancer," he said. "But you would have to take it for a very long time to reduce colon cancer -- perhaps 20 years or more."

He noted that some data suggest that "calcium supplementation may increase the risk of prostate cancer, so I personally shy away from recommending calcium supplementation for men. If I made any recommendation at all, it would be for women."

"Although the apparent lack of effect on advanced adenomas is disappointing, these data suggest that the protective effect of calcium on adenoma and hyperplastic polyps may extend up to 5 years after the cessation of active supplementation," Dr. Barry said.

[Presentation title: Prolonged Effect of Calcium Supplementation on Rick of Colorectal Adenomas. Abstract 2491]