Annual zoledronic acid to prevent gonadotropin-releasing hormone agonist-induced bone loss in men with prostate cancer: A randomized placebo-controlled trial

Abstract

4515 Background: Gonadotropin-releasing hormone (GnRH) agonists decrease bone mineral density (BMD) and increase fracture risk in men with prostate cancer. Zoledronic acid (4 mg IV every 3 months) increases BMD in GnRH agonist treated men. Intermittent zoledronic acid (4 mg IV once annually) increases BMD in postmenopausal women with osteoporosis but the efficacy of the annual treatment schedule in hypogonadal men is unknown. Methods: In a 12-month open-label study, men with nonmetastatic prostate cancer (n = 44) who were receiving a GnRH agonist were assigned randomly to zoledronic acid (4 mg IV × 1) or placebo. BMD of the posteroanterior lumbar spine and total hip were measured by dual energy x-ray absorptiometry at baseline and month 12. Serum N-telopeptide, a marker of osteoclast activity, was measured every 3 months. Results: Mean (± SE) BMD of the posteroanterior lumbar spine increased by 4.0 ± 0.9 in men treated with zoledronic acid and decreased by 3.1 ± 0.9 percent in men who received placebo (P < 0.001 for between-group comparison). BMD of the total hip decreased by 0.7 ± 0.6 percent in men treated with zoledronic acid and decreased by 1.9 ± 0.7 percent in men who received placebo (P = 0.005). Compared to placebo, zoledronic acid significantly decreased serum N-telopeptide throughout the 12-month study (P < 0.05). Conclusions: In men receiving a GnRH agonist for prostate cancer, a single treatment of zoledronic acid significantly increased bone mineral density of the total hip and spine at 12 months. Annual zoledronic acid may provide a convenient and effective strategy to prevent bone loss in hypogonadal men. This study was supported in part by Novartis Oncology and by the Prostate Cancer Foundation. [Table: see text]