High calcium levels may raise prostate cancer risk

NEW YORK (Reuters Health) - The results of a study published in the International Journal of Cancer indicate there is an association between dietary calcium and the risk of prostate cancer.

It has been suggested that increased consumption of calcium and dairy products raises the risk of prostate cancer, report Dr. Panagiota N. Mitrou, of the National Cancer Institute, Rockville, Maryland, and colleagues.

To further investigate, the researchers used data from the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study to examine dietary levels of calcium and dairy products and their relationship with prostate cancer risk. The ATBC study included 29,133 Finnish male smokers between the ages of 50 and 69 years old at study enrollment who completed a 276-item food questionnaire to assess the content of their diet.

During 17 years of follow-up, the team identified 1,267 cases of prostate cancer. A total of 27,028 participants had complete data available and were included in the final analysis.

“We found a strong, graded, positive association between calcium intake and total prostate cancer risk,” the researchers report. After adjusting the data for potentially influential variables, the risk of prostate cancer was 63 percent greater for subjects who consumed 2,000 milligrams per day or more of calcium compared with those who consumed less than 1,000 milligrams per day, a statistically significant difference.

A positive association was also observed between total dairy intake and prostate cancer risk, but this disappeared after eliminating the influence of calcium. In other words, the positive association between dairy fat and prostate cancer disappeared after calcium was eliminated, the authors note.

They point out that prostate specific antigen (PSA) screening, a marker for prostate cancer, has not been widely adopted in Finland. “Therefore, a large proportion of cases in our study were detected as a result of clinical symptoms,” Mitrou’s team explains. “This lessens the possibility that our results are influenced by detection bias.”

SOURCE: International Journal of Cancer, June 2007.