Science and good medicine is not always what it seems. We all believe that if something is logical it must be true, but often the most logical assumptions we make do not stand up to good scientific inquiry.
Many of us choke on the fact that Provenge extends life while it has no effect on our PSA. How can this be true, we all know that PSA scores allow us to have a window on our cancer, but the truth is that it does extend life without changing our PSA levels.
Taking calcium and vitamin D supplements while on hormonal therapy to treat our prostate cancer seems both logical and like good medicine. We all operate on the assumption that calcium and vitamin D will counter our risk of bone loss.
However, epidemiologists at Wake Forest Baptist Medical Center showed that calcium and vitamin D supplementation did not prevent bone loss and, in fact, may increase the risk of cardiovascular disease and aggressive prostate cancer. The study was published online in the July issue of the journal The Oncologist.
Gary Schwartz Ph.D. who is a prostate cancer epidemiologist who was the lead author in this study at Wake Forrest said, “It wouldn’t be so bad if there simply was no obvious benefit…. The problem is that there is evidence that calcium supplements increase the risk of cardiovascular disease and aggressive prostate cancer, the very disease that we are trying to treat.”
A major side effect of androgen deprivation therapy (ADT) in men is bone loss, or osteoporosis. Consequently, many physicians recommend calcium and vitamin D supplements to help reduce fracture risk in these men, which can be a significant problem. One in 10 of these men will experience a fracture within two years of therapy.
“Calcium and/or vitamin D supplementation to prevent loss of bone mineral density in these men seems so logical that no one had questioned whether it works,” said Mridul Datta, Ph.D., co-author of the study and a postdoctoral fellow who works with Schwartz at Wake Forest Baptist.
In the study, the researchers reviewed guidelines for calcium and/or vitamin D supplementation. They also reviewed the results of 12 clinical trials of supplemental calcium and/or vitamin D in a total of 2,399 men with prostate cancer undergoing ADT, as well as the measurements of bone mineral density before and after ADT.
“We used these data to determine whether calcium and vitamin D supplements prevented bone loss in these men,” Datta said. “The answer clearly is, ‘No!
The lack of an obvious benefit is worrisome because other data show an association between increased dietary calcium and an increased risk of aggressive prostate cancer and heart disease, Schwartz said.
The researchers did say that further research is needed to verify these findings.
“The wakeup call of these findings,” said Datta, “is that the presumption of benefit from calcium and vitamin D supplements that have been routinely recommended to these men must be rigorously evaluated.”
Co-author Mridul Datta, R.D., Ph.D., is supported by the Comprehensive Cancer Center of Wake Forest University Cancer Control Traineeship, NCI/NIH grant #R25CA122061.
Joel T Nowak, M.A., M.S.W.