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MONDAY, Jan. 19 (HealthDayNews) -- Men taking hormones to control prostate cancer need to be monitored and treated for osteoporosis, a new study says.

Although osteoporosis is most often associated with postmenopausal women, men also lose bone density as they age. And for men with prostate cancer, one of the most common therapies can speed up bone mineral loss and lead to osteoporosis and bone fractures, the new research confirms.

Prostate cancer is the most common cancer in men, and hormone therapy is a very important risk factor for developing osteoporosis, says lead researcher Dr. Terrence H. Diamond, an associate professor of medicine at the University of New South Wales in Australia.

Diamond notes this type of hormone therapy, called androgen deprivation therapy (ADT), which blocks the production of testosterone, is now commonly used in elderly men who have advanced or high-risk prostate cancer that is not suitable for more aggressive treatment.

In their study, Diamond and his colleagues reviewed all the literature related to ADT and osteoporosis and fractures from 1986 to 2000. Their conclusions are based on nine studies that included a total of 208 patients, according to their report in the Jan. 19 online issue of Cancer.

Diamond notes that, in some studies, bone mineral density measurements were up to 17 percent lower in men with prostate cancer treated with ADT than in men not receiving the hormone therapy.

And in other studies, after only 12 months of ADT therapy, ADT contributed to bone loss of up to 8 percent from the mid-spine and up to 6.5 percent from the neck of the femur -- the thigh bone. These losses in bone density may increase with time, Diamond says.

In addition, the researchers found fractures were more common among men receiving ADT compared with men not receiving ADT.

However, Diamond's team found drugs that prevent bone breakdown, called bisphosphonates, such as pamidronate and zoledronate can prevent bone loss and may even increase bone mass in these patients.

Diamond advises that since osteoporosis is usually a silent disorder, patients should request a full osteoporotic evaluation from their doctor before starting ADT. The evaluation should include bone density tests and X-rays. If necessary, patients should be treated with bone-building drugs, he adds.

Diamond's team is beginning a study of 1,000 men with prostate cancer receiving ADT. In the study, the men will be given either zoledronate or a dummy drug.

"This study will determine the 'true' fracture risk in these high-risk patients, as well as the efficacy of zoledronate for preventing bone loss and fractures," Diamond says.

Dr. Clifford Rosen, a professor of nutrition at the University of Maine, agrees that "fractures due to rapid bone loss from ADT is a significant cause of problems in men with prostate cancer."

Preventive therapy with bone-building drugs and calcium and vitamin D is essential to prevent painful fractures, he says.

"Although more work needs to be done, it is conceivable that the bisphosphonates may also reduce the risk of subsequent bone cancer, another serious complication of prostate cancer," he adds.

However, Rosen cautions there is clearly a need for more studies.

"This study provides some solid evidence for the need to have disease recognition and treatment," he says. "However, the number of studies and the number of subjects under investigation has been quite small. More research is desperately needed to better understand the risks of ADT and to clarify the best treatment approaches."

More information

To learn more about prostate cancer, visit the National Library of Medicine. For more on osteoporosis and men, check with the National Osteoporosis Foundation.

(SOURCES: Terrence H. Diamond, M.D., associate professor, medicine, University of New South Wales, Sydney, Australia; Clifford Rosen, M.D., professor, nutrition, University of Maine, Orono; Jan. 19, 2004, online issue, Cancer )

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