A prospective study of total and ionized serum calcium and fatal prostate cancer

We recently reported a significant positive association in the National Health and Nutrition Examination Survey between high levels of total calcium in serum, measured prospectively, and risk of fatal prostate cancer. To confirmthis, we examined associations between total and ionized serumcalciumand prostate cancer mortality in an independent cohort, the Third National Health and Nutrition Examination Survey. Twenty-five prostate cancer deaths occurred over 56,625 person-years of follow-up. Compared with men in the lowest tertile of total serumcalcium, the multivariate-adjusted relative risk for death fromprostate cancer for men in the highest tertile was 2.07 (95% confidence interval, 1.06-4.04). For ionized serumcalcium, the physiologically active fraction of total serumcalcium, the relative risk for men in the highest tertile was 3.18 (95% confidence interval, 1.09-9.28). These findings support the hypothesis that serumcalciumis a prospective biomarker of fatal prostate cancer.