High-Normal Calcium Levels Linked to Fatal Prostate Cancer

Tag : calcium

Comparison of the highest and lowest tertiles of serum calciumresulted in a hazard ratio of 2.68 for fatal prostate cancer, GarySchwartz, Ph.D., of Wake Forest University here, and Halcyon G.Skinner, Ph.D., of the University of Wisconsin in Madison, reportedin the September issue of Cancer Epidemiology, Biomarkers, and Prevention.
The analysis of data from the National Health and NutritionExamination Survey (NHANES) showed no association between serumcalcium and the occurrence rate of prostate cancer.
"To our knowledge, this is the first study to examine prostatecancer risk in relation to serum calcium," the authors said. "Theseresults support the hypothesis that high serum calcium, or a factorstrongly associated with it, such as high serum parathyroidhormone, increases the risk for fatal prostate cancer."
Impetus for the analysis came from the authors' interest in theassociation between serum parathyroid hormone and prostate cancer.In the normal state, parathyroid hormone helps maintain serumcalcium levels within a narrow range of about 9 to 10.5 mg/dL.
Prostate cancer cells express receptors for both parathyroidhormone and calcium. Moreover, laboratory studies have shown thatparathyroid hormone and calcium promote prostate cancer cell growthand metastasis.
Given that scientific background, the authors explored potentialassociations between serum calcium and prostate cancer, using datafrom NHANES I and the NHANES Epidemiologic Follow-Up Study. Theyidentified 2,814 men ages 24 to 77 for whom serum calciummeasurements were available.
During 46,188 person-years of follow-up, 85 cases of prostatecancer were diagnosed, and 25 men died of prostate cancer. The timefrom serum calcium measurement to prostate cancer diagnosisaveraged 9.9 years.
The study population was divided into tertiles on the basis ofmedian serum calcium levels: 9.3 mg/dL, 9.7 mg/dL, and 10.2 mg/dL.Comparison of the highest and lowest tertiles showed that men withhigher calcium levels were younger (45.5 versus 52.2) and morelikely to be black (15.4% versus 11.6%). The groups did not differwith respect to body mass index or family history.
In a multivariable-adjusted analysis, those with the highestcalcium levels had a significantly greater risk of fatal prostatecancer ( P =0.04) compared with those who had the lowest calcium levels.High-normal calcium was associated with a 31% greater risk ofdeveloping prostate cancer, but the difference did not reachstatistical significance.
The risk associated with high-normal serum calcium is comparable tothe risk conferred by a positive family history, the authors said.
If the findings are confirmed by other studies, the data havepotentially major implications for prevention.
"What is particularly exciting is that it suggests that a man mayreduce his risk of fatal prostate cancer by lowering serum levelsof calcium and/or parathyroid hormone," said Dr. Schwartz.