Bisphosphonates Reverse Bone Loss in Men with Prostate Cancer

SAN FRANCISCO—Bisphosphonate therapy administered intravenously (IV) every 3 months significantly increases bone mineral density (BMD) compared with placebo in androgen-deprived prostate cancer patients without bone metastases. This approach may also help recover some of the bone already lost, according to a new study presented at the 2006 Prostate Cancer Symposium.

This 12-month study included 120 men (mean age, 72 years; ≈10% African American) who had been receiving androgen therapy for up to 12 months for prostate cancer. Of these, 61 men were randomized to IV zoledronic acid (Zometa) every 3 months and 59 men to placebo.

Zoledronic acid had previously been shown to prevent BMD loss in patients with prostate cancer who were beginning hormone therapy. “What’s new about our study is that it shows starting zoledronic later is still effective and can recover bone density that already has been lost,” said lead investigator Christopher Ryan, MD, of the Oregon Health & Science University Cancer Institute in Portland.

Femoral neck, lumbar spine, and total BMD were measured using dual-energy x-ray absorptiometry at baseline, at 6 months, and then again at 12 months. The bone turnover markers, serum bone-specific alkaline phosphatase (BSAP) and urine N-telopeptide cross-links (NTx), were also measured at baseline and then every 3 months. The primary end point was change in femoral neck and lumbar spine BMD at 6 months and 12 months.

“Men in the drug arm gained bone, and men in the placebo arm lost bone, at the different sites. We weren’t surprised by this, because a previous study has found similar results. However, this was a slightly different patient population, and the findings were dramatic in terms of bone density improvement,” Dr Ryan told IMWR.

“This is an option primary care physicians may want to think about, especially in noncompliant patients. This is an intravenous treatment every 3 months instead of an oral bisphosphonate. I have patients who prefer this method.”

The men taking placebo lost an average of >2% of their BMD at the 2 sites, compared with an average increase of 3.6% in the femoral neck and 6.7% in the lumbar spine from baseline, with zoledronic acid.

Mean serum BSAP decreased by 13% and urine NTx concentrations by 53% in the treatment group. In contrast, men taking placebo had increases of 59% in mean serum BSAP and of 19% in urine NTx concentration.

Dr Ryan said that these findings support current guideline recommendations for the close monitoring of bone density in men receiving hormone therapy, along with aggressive management (ie, initiating bisphosphonate therapy if BMD declines) to help prevent osteoporosis and/or future fractures. “I don’t think you can always count on urologists to manage bone density, so it is important for primary care physicians to be aware of these data and partner with the urologists in managing the complications of androgen-deprivation therapy,” he noted.