Men with
prostate cancer are at high risk of developing bone
metastases that can lead to clinically significant skeletal morbidity. Recently, a randomized, placebo-controlled, phase III trial in 422 men with
hormone-refractory
prostate cancer and bone
metastases demonstrated that
zoledronic acid (4 mg every 3 weeks) significantly reduced the incidence and onset of skeletal complications and provided significant long-term reductions in bone
pain compared with placebo. Patients received
zoledronic acid for a 15-month core phase, with the option to continue
therapy for 9 more months on the extension phase. To evaluate the continuing benefit of long-term
zoledronic acid therapy, retrospective exploratory analyses were conducted based on the incidence of skeletal-related events (SREs; defined as pathologic
bone fracture,
spinal cord compression, surgery or
radiation therapy to bone, or change in
antineoplastic therapy for bone
pain) occurring only during the extension phase of this trial. Quality of life parameters included assessment with the Brief
Pain Inventory. Similar to results reported for the 15-month core phase and the entire 24-month study, the 9-month extension phase demonstrated that
zoledronic acid significantly reduced the percentage of patients with an SRE (P = 0.017), prolonged the median time to first SRE (P = 0.036), reduced the annual incidence of SREs by 52% (P = 0.016), and reduced the risk of SREs by 53% (P = 0.022) compared with placebo. Furthermore,
zoledronic acid was safe and well tolerated. Therefore,
zoledronic acid provides long-term continuing clinical benefit for men with
prostate cancer and bone
metastases and represents a new therapeutic option for this population.