Calcium Supplements Protects Against Colorectal Adenomas

Earlier research has demonstrated that people with noncancerous colorectal tumors called adenomas who take calcium supplements for four years can reduce their risk of an adenoma recurrence. A new study shows that the protective effect of those supplements lasts for up to five years after stopping supplementation.

In the Calcium Polyp Prevention Study, 930 individuals with a recent adenoma were randomly assigned to receive 4 years of daily 1200-mg calcium supplements or a placebo. The study revealed that those assigned to calcium supplements had a 17% lower relative risk of an adenoma recurrence than those who got the placebo.

In the study, which was published in the January 17, 2007, issue of the Journal of the [U.S.] National Cancer Institute, Maria V. Grau, M.D., John A. Baron, M.D., and colleagues from Dartmouth Medical School (Hanover, NH, USA) tracked 822 of the patients from that trial after the end of the treatment. Their goal 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 discovered that, in the first five years after the end of the treatment, individuals in the calcium group continued to have a lower risk of adenomas than those in the placebo group: 31.5% of people who had taken calcium had recurrences compared with 43.2% 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 investigators wrote in their article. "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.”

"Where do we go from here--and, more important, what public health recommendations related to calcium do we provide for risk reduction of colorectal cancer?” asked Maria Elena Martinez, Ph.D., and Elizabeth T. Jacobs, Ph.D., from the Arizona Cancer Center (Tucson, AZ, USA) who wrote an editorial piece in the same issue of the journal. They noted that current guidelines recommend that people only consume recommended levels of calcium (1000 mg/day for adults up to age 50 years and 1,200 mg/day for those older than 50 years). "Because no protection for colorectal cancer is apparent at higher levels of calcium intake, this recommendation is justified,” they wrote.




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