CHICAGO (AP) - Millions of women at high risk of breast cancer because of genes, family history or other reasons have a new option for preventing the disease.

A big study finds that a drug cut the risk of developing breast cancer by more than half in women who were past menopause. The drug is Exemestane (ex-eh-MESS'-tane), sold by Pfizer Inc. as Aromasin (ah-ROHM'-ah-sin) and in generic form.

Two drugs are already available for preventing breast cancer - tamoxifen (tah-MOCKS'-eh-fen) and raloxifene (rah-LOCKS'-eh-feen). But these are unpopular because they can cause blood clots and uterine cancer. The study did not find these side effects with the newer drug.

Results were discussed Saturday at a cancer conference in Chicago and published in the New England Journal of Medicine.

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