A drug used by women with osteoporosis has been approved to prevent fractures in cancer patients treated with hormones. But recent studies show that silent fractures often exist even before the hormone therapy starts.
The Food and Drug Administration this week approved denosumab (Prolia; Amgen) to increase bone mass and prevent fracture among women taking aromatase inhibitors for breast cancer, and among men receiving anti-androgen therapy because of prostate cancer. This is the first approval of a drug intended to prevent adverse effects on bone structure from cancer treatments that target hormones.
The approval is based on two Phase 3 trials, a 3-year randomized multinational study including 1,468 men treated with androgen deprivation therapy and a similar 2-year study involving 252 postmenopausal women treated with aromatase inhibitors for breast cancer. Both trials showed significant improvements in bone mineral density and reduced incidence of fractures among denosumab-treated subjects, compared to controls.
The approval is a hopeful sign for cancer patients at risk of fractures caused by their treatment, but for many cancer patients this may come too late. A recent prospective study from France found that 20% of postmenopausal women already had vertebral fractures at the time they began aromatase inhibitor treatment for breast cancer. Men with advanced prostate cancer appear to be at even greater risk: A prospective study from the UK found that more than half showed vertebral fractures on thoracolumbar x-rays before beginning androgen deprivation therapy.
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