Men undergoing androgen-deprivation therapy for nonmetastatic prostate cancer were enrolled at 156 centers in North America and Europe and randomly assigned to receive injections of either denosumab or a placebo every six months for three years. Participants were also instructed to take daily calcium and vitamin D supplements during the study period.

Among the more than 900 participants who completed the study, denosumab significantly increased bone density at all the monitored sites - including the lumbar spine, total hip and femoral neck - and reduced new vertebral fractures by 62 percent. Bone density at the radius, one of the bones in the forearm, also increased in the treatment group, an improvement not seen with other osteoporosis drugs. Few adverse events were associated with treatment, and there were no reports of osteonecrosis of the jaw, a problem reported in some patients taking bisphosphonates.

"Denosumab is an important new therapy to prevent painful fractures in prostate cancer survivors," Smith says. "An ongoing clinical trial will also evaluate whether denosumab prevents spread of prostate cancer to bone, the most common site of metastases in men with this disease." Smith is an associate professor of Medicine at Harvard Medical School.

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