Osteoporosis (bone loss) is one of several side effects which accompany androgen deprivation (hormonal) therapy (ADT). Fifty (50) percent of men will be affected by their fourth year of treatment, and more than 80 percent will be affected after10 years. The risk of fractures including those of the spine also increases with hormonal therapy treatment for a year or more. This enhanced risk is illustrated by a recent study in The New England Journal of Medicine where it was reported that “among men with prostate cancer who lived for at least five years after their diagnosis, the risk of a fracture was nearly 20 percent among androgen deprivation (hormonal) therapy users, compared with 13 percent for nonusers.” Men treated with hormonal therapy are generally advised to have annual bone density testing.
Medications are also often prescribed to halt bone loss. The well-known bisphosphonates (such as Fosamax) are the first treatments prescribed followed by selective estrogen receptor modulators (SERMs) such as tamoxifem, used in the treatment of breast cancer. For prostate cancer patients, a new alternative, a monoclonal antibody called denosumab (brand names Xgeva or Prolia), is now generating much attention. Denosumab is an injectable monoclonal antibody. Monoclonal antibodies are made to target and destroy only certain cells in the body thereby helping to protect healthy cells from damage. Xgeva is used to prevent bone fractures and other skeletal conditions in people with tumors that have spread to the bone. Prolia is another brand of denosumab used to treat osteoporosis in postmenopausal women who have high risk of bone fracture. In November 2010, the Food and Drug Administration (FDA) approved Prolia (Xgeva) to help prevent skeletal-related events in prostate cancer patients treated with hormonal therapy whose cancer had already metastasized to bone. The use of this therapy has recently been expanded. On Friday, September 16, 2011, the FDA approved denosumab (Prolia) in prostate cancer patients undergoing androgen deprivation (hormonal) therapy whose cancer had not yet metastasized to bone. Denosumab is also approved by the FDA for additional indications. The brand Prolia was approved by the FDA on June 1, 2010 for the treatment of postmenopausal women with osteoporosis who are considered to be at high-risk for fractures.
For more details, see the Johns Hopkins Health Alerts, “Prostate Cancer: Why You May be at High Risk for Osteoporosis,” Sept. 29th, 2011; and, “FDA Expands Approval for Denosumab”, NewsPulse from the Prostate Cancer Foundation, Sept. 30th, 2011;