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High-risk Women Wanted for Breast Cancer Prevention Study

Gwen Ericson

Oct. 19, 2005 – A drug potentially able to prevent breast cancer in high-risk women is the subject of a new clinical study at Washington University School of Medicine in St. Louis. The drug, called exemestane, belongs to a new class of breast-cancer drugs called aromatase inhibitors.

Compared to tamoxifen, a standard preventative, aromatase inhibitors have shown greater benefit in reducing recurrence of tumors in women who had previously been treated for breast cancer. The new multinational study will evaluate exemestane's effectiveness at preventing breast cancer from developing in the first place.

Sponsored by the National Cancer Institute of Canada, the study is recruiting post-menopausal women at high risk for developing breast cancer but who have not been diagnosed with cancer. Those at high risk include women with a family history of breast cancer and those who've had a biopsy showing an atypical growth. Participants will receive either exemestane or an inactive placebo and will be regularly screened for breast cancer.

"This is a very exciting new study," says Antonella Rastelli, M.D., instructor in medicine and a researcher with the Siteman Cancer Center. "Earlier data have shown that exemestane may be even better than tamoxifen at preventing breast cancer and has fewer side effects."

Tamoxifen has been linked to an increased incidence of uterine cancer, blood clots, and strokes. Aromatase inhibitors such as exemestane do not show these side effects.

"Exemestane works differently than tamoxifen," Rastelli says. "Both interfere with estrogen stimulation of breast cancer cell growth. Tamoxifen does this by blocking estrogen receptors on cancer cells, but exemestane completely halts the production of estrogen in the body."

The first trial of a preventative in women at risk but without breast cancer was published in 1998. That study looked at the effect of tamoxifen in over 13,000 high-risk women who received either tamoxifen or placebo. The study demonstrated that tamoxifen caused a 50 percent reduction in breast cancer development in this group.

This new study will recruit about 5,000 women at centers in the United States, Canada and Spain. Like the earlier tamoxifen study, it will compare the effect of a placebo to the active drug. Selection of who receives exemestane will be random and neither participants nor study leaders will know the treatment given until after the data are collected. The participants will be followed for five years.

Women in Missouri and Illinois regions surrounding St. Louis who would like to participate in the study at Washington University can call 314-362-7249 or 314-747-1171. Callers to the latter phone number should select option three on both the first and second menu they hear.


Last updated 10/20/05