A recent report revealed that men in the upper tertile of the normal distribution of serum calcium have an approximately 3-fold increased risk of fatal prostate cancer later in life.

The stimulus for this research came from recent work on the pathophysiology of metastatic prostate cancer (Schwartz GG. Prostate cancer, serum Parathyroid Hormone and the progression of skeletal metastases. Cancer Epidemiology Biomarkers & Prevention, 2008, 17: 478-83.) In that paper, it was suggested that parathyroid hormone (PTH) plays an important role in promoting the progression of prostate cancer metastases to bone.

If PTH is a “bad actor” in late stage disease it may also be a “bad actor” earlier in the natural history of prostate cancer. Although serum PTH is not commonly measured, serum calcium is. In healthy persons, most instances of hypercalcemia are due to elevated PTH. Thus, the researchers used population-based data on serum calcium levels as a surrogate for PTH levels using the NHANES survey in which serum calcium levels were measured. They then followed-up participants with high serum calcium and showed that they had a significantly increased rate of fatal prostate cancer.

What’s the “ take-home message”?

Elevations of serum calcium within the normal range are associated with a significantly increased risk of fatal, but not incident prostate cancer. These findings have implications for identifying men at high risk of fatal disease while minimizing the risk of over-detection of prostate cancers that are not life-threatening.

Whether the increased risk observed is due to calcium itself or to parathyroid hormone is unknown. Both factors have been shown to promote the growth and metastasis of prostate cancer cells in the laboratory. Because there are oral medications that can effectively suppress either PTH and/or calcium, it may be possible to reduce risk of fatal disease by lowering one of both of these factors in men who present with high levels of calcium and/or PTH in serum. Thus, these findings may lead to medical interventions to prevent fatal disease. The researchers are presently working to confirm these findings in other prospective cohorts (Newswise).