Skeletal complications in patients with bone metastases from renal cell carcinoma and therapeutic benefits of zoledronic acid

Bone metastases in patients with renal cell carcinoma are associated with a high risk of skeletal complications. Therefore, a subset analysis of a larger clinical trial was performed to determine the efficacy of zoledronic acid in renal cell carcinoma patients. Patients with bone metastases from solid tumors other than breast or prostate cancer (n = 773) were randomized to receive zoledronic acid or placebo via 15-minute infusion every 3 weeks for 9 months. Patients were monitored for skeletal-related events, which were defined as pathological fracture, spinal cord compression, radiotherapy, or surgery to bone. Among the subset of 74 patients with renal cell carcinoma, 46 patients were treated with 4 mg of zoledronic acid or placebo. Significantly fewer patients treated with 4 mg zoledronic acid had a skeletal-related event (37% versus 74% for placebo, P = 0.015), and zoledronic acid significantly prolonged the time to first skeletal-related event (median not reached at 9 months versus 72 days for placebo; P = 0.006). Zoledronic acid significantly reduced the annual incidence of skeletal-related events by similar to21% (mean 2.68 versus 3.38 events per year for placebo, P = 0.014) and significantly reduced the risk of developing a skeletal-related event by 61% compared with placebo (risk ratio = 0.394, P = 0.008) by multiple event analysis. Median time to progression of bone lesions was also significantly extended with zoledronic acid treatment (P = 0.014). Zoledronic acid is the first bisphosphonate to significantly reduce skeletal morbidity and significantly prolong time to bone lesion progression in patients with bone metastases from renal cell carcinoma.