Letrozole in Preventing Breast Cancer in Postmenopausal Women With a BRCA1 or BRCA2 Mutation

DISEASE CHARACTERISTICS: * Must meet the following criteria: * With or without invasive unilateral breast cancer more than 5 years ago, with no recurrence * No evidence of breast cancer by mammography or MRI within the past year * Carrier of the BRCA1/BRCA2 deleterious mutation (nonsense mutation or stop) * Refused preventive mastectomy * No prior bilateral breast cancer * No prior bilateral mastectomy * Hormone receptor status not specified PATIENT CHARACTERISTICS: Inclusion criteria: * Menopausal status as indicated by 1 of the following criteria: * Age \> 60 years * Bilateral oophorectomy * Age ≤ 60 years with no hysterectomy or amenorrhea within the past 12 months * Age ≤ 60 years with prior hysterectomy or FSH \> 20 IU/L * Eastern Cooperative Oncology Group (ECOG) or WHO performance status 0-1 * absolute neutrophil count (ANC) \> 2,000/mm\^3 * Platelet count \> 100,000/mm\^3 * Hemoglobin \> 10 g/dL * Bilirubin normal * ALT and AST \< 2.5 times upper limit of normal * Creatinine clearance ≥ 60 mL/min * Adequate cardiovascular function (e.g., no history of myocardial infarction, angina pectoris, or heart failure) * No osteoporosis by bone density scan (DEXA) within the past 2 years or prior osteoporotic fracture (femur, lumbar spine T score \> -2 DS) Exclusion criteria: * Invasive cancer diagnosed in the past 5 years, except for basal cell or squamous cell skin cancer or carcinoma in situ of the cervix * Prior cerebrovascular accident * Prior car…