Serum Calcium And Incident And Fatal Prostate Cancer In The National Health And Nutrition Examination Survey

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Cancer / Oncology
Article Date: 19 Sep 2008 - 8:00 PDT

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UroToday.com - In our recent report, we show 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. Readers intrigued by these findings may have several questions:

Why would we conduct such an analysis in the first place?

The stimulus for this research came from our 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, we summarized research suggesting that parathyroid hormone (PTH) plays an important role in promoting the progression of prostate cancer metastases to bone.

We reasoned that 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, we reasoned that we could use population-based data on serum calcium levels as a surrogate for PTH levels using the NHANES survey in which serum calcium levels were measured. We 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.

What do we need to know and What's next?

Whether the increased risk we 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. We are presently working to confirm these findings in other prospective cohorts.

Written by Gary G. Schwartz, PhD, MPH, as part of Beyond the Abstract on UroToday.com

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