The effect of zoledronic acid on bone mineral density in patients undergoing androgen deprivation therapy.

PURPOSE: The aim of this study was to evaluate the efficacy and safety of zoledronic acid compared with placebo in preventing bone mineral density (BMD) loss and suppressing bone markers when initiated during the first year of androgen deprivation therapy in patients with locally advanced prostate cancer.

PATIENTS AND METHODS: Patients were randomized to receive zoledronic acid 4 mg or placebo intravenously every 3 months. Lumbar spine (LS) and total hip BMD was measured using dual-energy x-ray absorptiometry at baseline and at week 52. N-telopeptide (NTX) and bone-specific alkaline phosphatase (BSAP) were evaluated at baseline and every 12 weeks. Safety assessments were performed throughout the study.

RESULTS: Efficacy analyses included 106 patients and 109 patients in the zoledronic acid and placebo groups, respectively. At week 52, the least squares mean BMD percentage differences were 6.7% for LS and 3.7% for total hip (P < 0.0001 for both). In the zoledronic acid group, decreases in NTX ((-)14% to (-)28%) and BSAP ((-)31% to (-)37%) levels were significant and sustained; changes in NTX levels and LS BMD (r = (-)0.25; P = 0.04) and in BSAP levels and hip BMD (r = (-)0.28; P = 0.02) were significantly correlated. Only traumatic fractures were reported for 2 and 3 patients receiving zoledronic acid and placebo, respectively. One patient in each group experienced acute renal failure. Osteonecrosis of the jaw was not reported.

CONCLUSION: Zoledronic acid (4 mg intravenously every 3 months) was safe and effective in preventing bone loss and reducing bone turnover in patients with prostate cancer when initiated during the first year of androgen deprivation therapy; patients with low baseline BMD experienced the greatest benefit.