CHICAGOZoledronic acid (Zometa) significantly decreased skeletal complications and bone pain in men with hormone-refractory prostate cancer and bone metastases, compared with placebo, according to an update of a phase III study presented at the 2003 Annual Meeting of the American Urological Association (abstracts 1472 and 1473).
After 24 months of follow-up, the percentage of men who had at least one skeletal-related event was 49% in the placebo group vs 38% in the treatment group, a relative reduction of 22% and an absolute reduction of 11%, reported Fred Saad, MD, associate professor of urology and director of urology oncology, Montreal Cancer Center, University of Montreal.
Among men treated with zoledronic acid(Drug information on zoledronic acid), there was a 5-month delay in the median time to the first skeletal-related event and a 6.5-month delay in the time to the first pathologic fracture, compared with placebo.
"Probably the most important endpoint was the multiple event analysis that took into consideration the proportion of patients having skeletal-related events, the time between events, and the number of events that occurred per patient," Dr. Saad said. In the multiple events analysis, the risk of developing a skeletal complication was 36% lower for patients treated with the bisphosphonate (P = .002).
Differences in pain scores between zoledronic acid and placebo were statistically significant at 3, 9, 21, and 24 months. Men treated with zoledronic acid also had significantly less need for radiation treatments directed to bone, which suggests that the bisphosphonate provides improved pain control, Dr. Saad said.
"There were few adverse events that were unexpected, and renal toxicities were limited and identical to placebo at the 4-mg zoledronic acid dose. So we feel this is a new treatment option for patients with metastatic prostate cancer," he said.
When asked his opinion about the possible use of zoledronic acid earlier in the prostate cancer disease process, Dr. Saad said, "My gut feeling is that it will have a benefit, but we need a study to prove it. That is the next logical step, and a study is going to be started very shortly on that topic."