High Blood Calcium Levels Put Men at Greater Risk For Fatal Prostate Cancer

Prostate cancer is the second most common form of cancer in men, with about 780,000 men being diagnosed annually. It is the sixth mostly deadly form of cancer in men, causing approximately 250,000 deaths annually, according to the American Cancer Society. For years, doctors have searched for ways to predict whether prostate cancer patients will develop a tumor of little threat, or one that will become fatal. Although blood calcium has not been found to be very predictive of whether a man will get non-lethal prostate cancer, it has been found in a recent study to be very indicative of those men who will develop fatal prostate cancer tumors.
According to the new study published by U.S. researchers, the findings suggest that the use of a simple blood test can assist in identifying men who are at elevated risk for the development of potentially fatal prostate tumors. Once identified, these men can be treated with readily available drugs that decrease calcium levels in the bloodstream including Fontus Pharmaceuticals Incorporated's Rocaltrol, also called calcitriol; Genzyme Corporation's Hectorol (doxercalciferol); Abbott Laboratories' Zemplar (paricalcitol); and Amgen Incorporated's Sensipar (cinacalcet).
The researchers followed 2,814 men in who participated in the National Health and Nutrition Examination Survey (NHANES) and the NHANES Epidemiologic Follow-up Study. The men gave blood samples that revealed calcium levels that showed a direct link between the levels and the risk of fatal prostate cancer.
The research group found that men in the top one-third of high blood calcium levels were 2.68 times more likely to develop fatal prostate cancer in their lifetime when compared to men in the group who were in the bottom one-third. The percentage of those with the highest calcium levels and greatest risk for developing prostate cancer was found to be comparable in magnitude with the risk associated with family history.
A total of 85 cases of prostate cancer and 25 prostate cancer deaths occurred throughout the years of study follow-up (46,188 person-years). The blood samples given by participants were given, on average, about a decade before the cancer appeared.
Gary Schwartz of Wake Forest University School of Medicine, who helped lead the study, said in a telephone interview, "If serum calcium really does increase your risk for fatal prostate cancer, that's wonderfully exciting because serum calcium levels can be changed." Schwartz also added, "One way to think of it is to think of the tremendous advances in the control of cardiovascular disease that occur from understanding that things like serum cholesterol predict heart attack."
Schwartz noted that it is unclear whether actual calcium blood levels or blood levels of parathyroid hormone, which performs the function of keeping calcium levels in the body at normal levels in the bloodstream that increases the risk for prostate cancer. He explained that people who are treated for high blood calcium commonly have chronic kidney disease, which is associated with low vitamin D levels. Low vitamin D levels elevate parathyroid hormone levels.
Another researcher, Halcyon Skinner of the University of Wisconsin, said there is little relationship between calcium in the diet and blood calcium levels. Therefore, men at greater risk for prostate cancer would not benefit from eating less calcium rich food.
The findings of the study appear in the American Association for Cancer Research's journal Cancer Epidemiology, Biomarkers & Prevention.