Study Links Serum Calcium, Prostate Cancer Death

Serum calcium levels have almost nothing to do with dietary calcium intake, Schwartz emphasized. Serum calcium levels are tightly regulated and are characteristic of an individual in the same way as body temperature and height, he said. Thus, whether an individual eats a diet rich in cheese and milk or not, serum calcium levels generally do not vary by more than about 2 percent; instead, people are probably genetically predisposed to have one level or another, Schwartz explained.

The real "eye-opener," he said, is that, should the results be validated in other studies, serum calcium would represent one of the most significant known risk factors for prostate cancer, and the only one that could be clinically modified.

"The relative risk of prostate cancer for being black is about two, and the relative risk for having a positive family history is about 2.5. So a relative risk greater than 2.5 is actually bigger than anything we know," he said. "But what makes this really interesting is, if this is causal, it can be changed with medicine."

First, though, the results must be validated in other studies, Brooks noted. Researchers must then determine whether calcium itself actually causes this increased risk or is merely a marker of some other biological process. Either way, should the data be borne out, Brooks suggested another possible use of serum calcium.

Given that most cases of prostate cancer never become aggressive, "Maybe we could use those values to guide medical treatment, to decide who needs more aggressive therapy," he said. "It could be one factor in helping make a treatment decision."

More information

For more about prostate cancer, visit the National Cancer Institute.

SOURCES: Gary G. Schwartz, Ph.D., M.P.H., associate professor, cancer biology and epidemiology and prevention, Wake Forest University Health Sciences, Winston-Salem, N.C.; Durado Brooks, M.D., M.P.H., director, Prostate & Colorectal Cancer, American Cancer Society, Atlanta; September 2008,Cancer Epidemiology, Biomarkers & Prevention