For Release: January 17, 2007
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Calcium Supplements Extend Protection against Polyps

HANOVER, NH—Calcium supplements prolong protection against colorectal adenomas in high-risk patients, Dartmouth researchers report in the January 17 issue of the Journal of the National Cancer Institute. Adenomas — polyps— are non noncancerous tumors that may progress to colorectal cancer.

Dr. John A. Baron
(photo by Jon Gilbert Fox)

People with adenomas who take calcium supplements for four years can reduce their risk of an adenoma recurrence, previous research has shown. Now, a new Dartmouth Medical School study shows that the protective effect of those supplements lasts for up to five years after stopping active treatment.

The research follows up the Dartmouth-led Calcium Polyp Prevention Study. In that trial, 930 people with a recent adenoma were randomly assigned to receive four years of daily 1200-milligram calcium supplements or a placebo. Those assigned to calcium supplements had a 17 percent lower relative risk of an adenoma recurrence than those who got the placebo.

In the current research, Drs. Maria V. Grau, John A. Baron, and colleagues followed 822 of the patients from the earlier study after the end of the treatment. Their aim was to compare the risk of recurrence among participants who had taken calcium with the risk among those who had taken a placebo.

The researchers found that, in the first five years after the end of the treatment, people in the calcium group continued to have a lower risk of adenomas than those in the placebo group: 31.5 percent of people who had taken calcium had recurrences compared with 43.2 percent of those originally in the placebo group. However, after five years, this protective effect disappeared.

"Our study provides further evidence of the potential of calcium as a chemopreventive agent against colorectal adenomas among individuals with a history of these tumors," the authors write. "Our data indicate that, in these patients, the protective effect of calcium may extend for up to five years after the cessation of active treatment." The Dartmouth Medical School authors also include Kristin Wallace, Elizabeth Barry, Bernard Cole and Richard Rothstein.

Current guidelines for calcium levels are 1000 mg/day for adults up to age 50 years and 1200 mg/day for those older than 50 years. In an editorial Drs. Maria Elena Martinez and Elizabeth T. Jacobs of the Arizona Cancer Center write, "Because no protection for colorectal cancer is apparent at higher levels of calcium intake, this recommendation is justified."


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