To treat men with prostate cancer, physicians often employ “androgen-deprivation therapy”—drugs that reduce levels of the male hormones that promote the growth and proliferation of prostate cancer cells. Unfortunately, this therapy also decreases bone density and increases the chance of bone fracture. Despite this danger—and despite studies failing to find the therapy effective in many prostate cancer cases—the use of androgen-deprivation therapy has continued to rise in recent years.
That may change, though, thanks to a study by a group of UTMB researchers with the Sealy Center for Aging. Drawing on a sample of 50,613 men age sixty-six and older who had been diagnosed with prostate cancer, the scientists found that the relative risk of bone fracture was directly related to the number of doses of androgen-depriving drugs received. Patients given nine or more doses in the year after prostate cancer diagnosis were 45 percent more likely to suffer a fracture than those who did not receive the treatment and had a 66 percent greater risk of suffering a fracture that required hospitalization. The same patients also had a 62 percent greater risk of fractures typically associated with osteoporosis, such as those of the hip, spine, and forearm.
“In prostate cancer patients, who tend to be older, research has shown that fractures are associated with increased mortality, so it’s important to know just how much androgen-deprivation therapy increases the risk of fractures,” says Vahakn B. Shahinian, a UTMB assistant professor of internal medicine and lead author of the study, which appeared in the January 13, 2005, issue of The New England Journal of Medicine. “We found out that androgen-deprivation therapy increases the risk of fractures significantly.”
Calculating based on the 220,000 cases of prostate cancer diagnosed in the United States each year (prostate cancer is second only to skin cancer in frequency) and the more than 40 percent of patients who receive androgen-deprivation therapy, Shahinian and his co-authors—Assistant Professor Yong-Fang Kuo, Professor of Internal Medicine and Geriatrics Jean Freeman, and Sealy Center for Aging director James S. Goodwin—estimated that annually approximately three thousand excess fractures can be attributed to the treatment. Since many older men die with prostate cancer but not of it, for that group, at least, the androgen-deprivation“cure” may prove worse than the disease.
“The benefits of this therapy are uncertain, but physicians have been using it heavily—it’s hard to tell a patient that he has cancer and then say we’re not going to do anything, we’re just going to monitor it,” Shahinian says. “With these risk numbers, hopefully we’ll be able to make better-informed decisions.”