One way to treat prostate cancer is to cut back on the amount of testosterone and related hormones circulating in the body, which can shrink a prostate tumor or slow its growth. But, as with most medical treatments, there are drawbacks to hormone therapy, including a possible risk of bone fractures.

What the researchers wanted to know: Does hormone therapy for prostate cancer increase the risk of bone fractures?

What they did: The researchers used data from the National Cancer Institute and Medicare to look at 50,613 men ages 66 and older who were diagnosed with prostate cancer. They compared men who didn't have any hormone therapy—also known as androgen deprivation therapy—with those who either took drugs to block testosterone production or had testes removed. The researchers were looking for fractures that happened more than 12 months after the cancer was diagnosed (they figured that earlier fractures couldn't necessarily be attributed to the therapy).

What they found: Men who had hormone therapy were more likely to break a bone later; 19.4 percent of the men who had hormone therapy had a fracture, compared with only 12.6 of those who did not have the therapy. The researchers calculated how much this kind of therapy increases the risk of fracture; for example, men taking nine or more doses of the drug (gonadotropin-releasing hormone agonist) in the year after diagnosis had a 45 percent higher risk of breaking any bone and a 62 percent higher risk of breaking a bone usually associated with osteoporosis, such as the hip, spine, or forearm. The risks are similar with orchiectomy.

What the study means to you: Obviously, doctors shouldn't stop recommending hormone therapy just because it causes fractures. But the researchers write that the therapy is usually prescribed to men for whom there is no proven benefit. In those cases, they say, the risk of fracture should be weighed against the lack of evidence for a benefit.

Caveats: The researchers looked only at doses of the drug in the first year; taking it longer could increase the risk.

Find out more: Women aren't the only ones who get osteoporosis, according to an article from the American Academy of Family Physicians.

Information on hormone therapy for prostate cancer from the American Cancer Society

Read the article: Shahinian, V.B. et al. "Risk of Fracture After Androgen Deprivation for Prostate Cancer." New England Journal of Medicine. Jan. 13, 2005, Vol. 352, No. 2, pp. 154-165.

Abstract online: http://content.nejm.org