Researchers are embarking on a clinical trial to evaluate the ability of a new estrogen-suppressing drug, exemestane, to prevent breast cancer in women at increased risk for the disease.

The five-year study, led by renowned breast cancer researcher Dr. Paul Goss, will track more than 4,500 postmenopausal women in Canada, the United States and Spain. Researchers say it will include women at increased risk for breast cancer due to risk factors such as age, family history, age at first menstrual period, and age at first live birth.

Goss, who is conducting a number of ongoing treatment studies with this class of drugs, said the prevention trial — launched Wednesday — was 10 years in the planning.

Exemestane, which belongs to the aromatase inhibitor family of drugs, suppresses estrogen production, a key component in the development of some types of breast cancer.

The drug was approved in 1999 by the U.S. Food and Drug Administration for treatment of advanced breast cancer in women whose tumors have stopped responding to tamoxifen.

"For us it's the real cherry on the cake and we're very, very excited about it," Goss said from Boston, where he is director of breast cancer research at Massachusetts General Hospital Cancer Center.

"We're fairly sure it's going to work well too."

The trial is being co-ordinated by the National Cancer Institute of Canada clinical trials group and is funded in part by the Canadian Cancer Society.

(Xinhua News Agency/Agencies April 1, 2005)