Exemestane reduced the risk of a first invasive breast cancer by 65% in healthy postmenopausal women with risk factors for breast cancer, and also reduced the risk of known breast cancer precursor lesions, including ductal carcinoma in situ, lobular carcinoma in situ, atypical ductal hyperplasia, and atypical lobular hyperplasia, according to results of the randomized, placebo-controlled MAP.3 trial.