Michaelson MD et al. (2007) Randomized controlled trial of annual zoledronic acid to prevent gonadotropin-releasing hormone agonist-induced bone loss in men with prostate cancer. J Clin Oncol 25: 1038–1042

Gonadotropin-releasing-hormone (GnRH) agonists are routinely used to manage recurrent nonmetastatic prostate cancer, but the therapy results in hypogonadism, which has adverse consequences including osteoporosis. Zoledronic acid in 3-monthly doses has been shown to increase BMD in these patients; however, because high doses are associated with serious side effects, less frequent administration would be preferable. In a randomized, placebo-controlled study Michaelson et al. assessed the effect of a single, annual infusion of zoledronic acid on bone loss and BMD in men with nonmetastatic prostate cancer treated with GnRH agonists.

Eligible patients identified by bone scanning received either zoledronic acid 4 mg (n = 22) or placebo (n = 22) intravenously on day one of the study. All participants continued GnRH treatment for the duration of the study; 36 completed BMD testing at 12 months. In the placebo group BMD (mean ± SE) decreased by 3.1% ± 1.0% in the lumbar spine and by 1.9% ± 0.7% in total hip from baseline. By contrast, in the zoledronic acid group BMD increased by 4.0% ± 1.0 in the lumbar spine and 0.7% ± 0.5% in total hip. In addition, sustained decreases in levels of bone turnover markers were seen in the zoledronic acid group, in contrast to increases in the placebo group. No serious adverse effects were noted in either group.

The authors conclude that annual zoledronic acid therapy could be an effective therapy to prevent bone loss in hypogonadal men.