WEDNESDAY, Feb. 23 (HealthDay News) -- A new drug called denosumab (Xgeva) performed somewhat better than the current standard treatment of zoledronic acid (Zometa) for preventing fractures and other bone problems in men with hormone-resistant prostate cancer, a new study suggests.

In many patients, prostate cancer becomes resistant to initial hormone treatment within the first few years of diagnosis. As a result, tumors begin to grow again and spread to other parts of the body, including bones. This increases the risk of fractures and other bone problems that cause pain and disability, which can greatly reduce a man's quality of life, according to background information in the study.

Helping to prevent these bone troubles can prove very important to these patients, one expert said.

"The successful treatment of osteoporosis, bone pain, and complications of advanced boney disease in men with [castration]-resistant prostate cancer will increase their quality of life considerably," noted Dr. Elizabeth Kavaler, a urology specialist at Lenox Hill Hospital in New York City. She was not involved in the new study.

The research, which was funded by Xgeva's maker, Amgen, was led by Dr. Karim Fizazi of the University of Paris Sud, in France, and included more than 1,900 men. The men were treated for hormone-resistant prostate cancer at 342 centers in 39 countries. They were randomly assigned to receive either 120 milligrams of denosumab, delivered subcutaneously (needle just under the skin) plus an intravenous placebo (950 patients) or 4 milligrams of IV zoledronic acid plus IV placebo (951 patients), given every four weeks.

All the patients were advised to take supplemental calcium and vitamin D to help strengthen their bones. This advice was followed by 90 percent of patients in the denosumab group and 87 percent of those in the zoledronic acid group.

The median time to the first bone problems was just under 21 months in the denosumab group and a little more than 17 months in the zoledronic acid group.

Overall, bone problems occurred in 36 percent of patients who took denosumab and 41 percent of those who took zoledronic acid.

"The 5 percent reduction in skeletal related events, including pathologic fractures and spinal cord compression, seen in the denosumab group versus the zoledronic acid group is very encouraging," Kavaler said. "This is a difficult patient population in that their symptoms related to bone metastases can be debilitating."

Serious adverse events were recorded in 63 percent of patients in the denosumab group and 60 percent of those in the zoledronic acid group.

Of the adverse events most likely related to the treatments, hypocalcaemia (very low calcium concentrations) occurred in 13 percent of patients taking denosumab and in 6 percent of those taking zoledronic acid, while osteonecrosis of the jaw (a debilitating destruction of bone tissue) occurred in 2 percent of the denosumab group and 1 percent of the zoledronic acid group.

The study appears online Feb. 24 in the journal The Lancet.

More information

The U.S. National Cancer Institute has more about prostate cancer.