Letrozole in Postmenopausal Women at Increased Risk for Breast Cancer

The purpose of this study to see what happens to breast density in healthy postmenopausal women after treatment with letrozole in one year, compared with treatment with placebo for one year. Other goals of the study include determining if there is a connection between estrogen level and breast density for women in the study and collecting information about the quality of life of those taking part in the study.