By Liz Szabo
Februaary 26, 2007

ORLANDO — A breast cancer drug could help men with prostate cancer avoid some dangerous side effects of treatment, a study shows.

Toremifene may help protect men from heart disease and bone fractures, according to an interim analysis of 200 men in a trial of 1,392 patients.

About one-third of the 2 million Americans with prostate cancer are treated with a therapy that blocks testosterone, which can feed tumors, says Matthew Smith, associate professor at Massachusetts General Hospital Cancer Center.

Hormone-deprivation therapy is a mainstay of treatment for men in advanced stages of the disease and is sometimes given to men with early tumors as well, Smith says. He presented his research here Friday at the Prostate Cancer Symposium. The therapy doesn't cure cancer, but it can slow it down and ease pain.

Doctors have grown concerned about the therapy's side effects, however.

The treatments make men put on weight, gain fat and lose muscle, says Smith, the paper's lead author. In September, Smith published a paper showing that hormone deprivation also raises the risk of diabetes and heart disease. Another study presented Saturday confirmed those findings: Men over 65 on hormone-deprivation medications are more likely to die from heart disease.

Toremifene, a selective estrogen receptor modulator similar to tamoxifen, is approved to treat advanced breast cancer. Doctors also are testing it as a way to prevent prostate cancer in men with precancerous growths.

In this study, men with advanced cancer who took hormone-deprivation therapy were randomly assigned either toremifene or a sugar pill for two years. Patients who took toremifene gained bone density. Those on placebos lost bone. Men who took the drug also improved their cholesterol compared with the other patients, the study showed. It was financed by toremifene's manufacturer, GTx Inc.

Doctors also will measure if toremifene relieves other side effects of hormone deprivation, such as hot flashes and breast enlargement, Smith says. He doesn't expect it to relieve side effects such as impotence.

Experts at the conference who were not involved in the study said they're encouraged by toremifene's results.

But Howard Scher, chief of genitourinary oncology at New York's Memorial Sloan-Kettering Cancer Center, says doctors must wait for the study's final results to see whether toremifene reduces bone fractures.

Men who take hormone therapy tend to fear bone fractures more than any other side effect, says Dean Bajorin, an attending physician at Sloan-Kettering. Fracturing a bone can leave men disabled and may even shorten survival.