To evaluate the efficacy and safety of zoledronic acid in preventing bone loss in patients with hormone-sensitive prostate cancer and bone metastases who were receiving androgen deprivation therapy.

Patients received zoledronic acid 4 mg as a 15-minute infusion every 3 weeks for 1 year. Bone mineral density of the lumbar spine (L2 to L4) and total hip was measured by dual-energy x-ray absorptiometry at baseline and 12 months. Biochemical markers of bone turnover (N-telopeptide and bone alkaline phosphatase) and serum creatinine levels were evaluated at baseline and during the study. Skeletal-related events were assessed at each study visit.

Of the 221 enrolled patients, 202 and 221 patients were included in the efficacy and safety analyses, respectively. The mean increase in bone mineral density of the lumbar spine and total hip was 7.7% (P <0.001) and 3.6% (P <0.001), respectively. Decreases in N-telopeptide and bone alkaline phosphatase levels were significant and sustained. The median time to the first skeletal-related event was not reached; 11.9% of patients had a skeletal-related event. Arthralgia (20.4%), nausea (14%), fatigue (14%), and back pain (12.2%) were the most common adverse events. Adverse events due to renal function deterioration were infrequent. The mean maximal change in serum creatinine level from baseline was 0.3 mg/dL.

Zoledronic acid administration for 1 year to patients with hormone-sensitive prostate cancer and bone metastases who were receiving androgen deprivation therapy was safe and prevented bone loss, as demonstrated by significant increases in bone mineral density and sustained suppression of biochemical markers of bone turnover.