Exemestane in Reducing Breast Density in Postmenopausal Women at Risk for Breast Cancer

DISEASE CHARACTERISTICS: Radiologically confirmed density occupying at least 25% of the breast tissue on baseline mammogram* Grade 2, 3, 4, 5, or 6 (Boyd classification) Participants with different grades between the 2 breasts should be classified according to a higher grade NOTE: *Performed within 6 months before study entry Bone mineral density T-score of either posterior-anterior spine or hip (femoral neck) must be no greater than 2.0 standard deviations below the mean value of peak bone mass in young normal women as determined by DEXA scan within the past 6 months No concurrent breast cancer No prior invasive breast cancer or ductal carcinoma in situ No breast implants Hormone receptor status: Not specified PATIENT CHARACTERISTICS: Age Postmenopausal Sex Female Menopausal status Postmenopausal, defined as 1 of the following: Over 50 years of age with no spontaneous menses for at least 1 year 50 years of age and under with no menses (e.g., spontaneous or secondary to hysterectomy) within the past year AND a follicle-stimulating hormone level within institution postmenopausal range Bilateral oophorectomy Performance status Not specified Life expectancy Not specified Hematopoietic Not specified Hepatic Not specified Renal Not specified Cardiovascular No cardiovascular disease No history of myocardial infarction No history of stroke No uncontrolled high blood pressure Other No uncontrolled metabolic or endocrine disease No malabsorption syndrome No known hypersensitivity to exemestane or its excipients No other malignancy within the past 5 years except curatively treated squamous cell or basal cell skin cancer or carcinoma in situ of the cervix PRIOR CONCURRENT THERAPY: Biologic therapy No prior immunotherapy No concurrent immunotherapy Chemotherapy No prior chemotherapy No concurrent chemotherapy Endocrine therapy More than 3 months since prior exogenous estrogen and/or progesterone/progestin therapy More than 6 months since prior selective estrogen-receptor modulators (e.g., tamoxifen, toremifene, or raloxifene) No concurrent selective estrogen-receptor modulators (e.g., tamoxifen, toremifene, or raloxifene) No concurrent steroids Vaginal estrogens allowed (e.g., Estring® or Vagifem®) No concurrent compounded creams Radiotherapy Not specified Surgery Not specified Other More than 4 weeks since prior investigational agents No other concurrent medications that would preclude study endpoints No concurrent over-the-counter products or supplements considered to have an estrogenic effect, including any of the following: Ginseng Ginkgo biloba Black cohosh Dong quai Fortified soy supplements (e.g., phytoestrogen preparations)