Letrozole With or Without Zoledronate in Treating Healthy Postmenopausal Women With High Breast Density

DISEASE CHARACTERISTICS: * Healthy participant * Postmenopausal for \> 5 years * Breast density ≥ 50% by digitized mammography * No history of breast cancer, breast implant, or gynecological malignancy * No osteoporosis or postmenopausal fractures * T-scores ≥ -2.0 by dual-energy x-ray absorptiometry (DEXA) scan PATIENT CHARACTERISTICS: Age * 18 and over Sex * Female Menopausal status * See Disease Characteristics Performance status * ECOG 0-1 Life expectancy * Not specified Hematopoietic * Not specified Hepatic * AST or ALT ≤ 3 times normal Renal * Creatinine ≤ 1.5 mg/dL Cardiovascular * No cardiac disease Other * Nonsmoker * Vitamin D ≥ 15 ng/mL * No history of chronic medical or psychiatric condition or laboratory abnormality that would preclude study compliance or participation * No alcohol consumption of \> 2 alcoholic drinks per day * No malabsorption PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * Not specified Endocrine therapy * At least 1 year since prior hormone replacement therapy * No concurrent steroids, parathyroid hormone, or raloxifene Radiotherapy * Not specified Surgery * Not specified Other * No other concurrent medication known to affect calcium and bone metabolism (e.g., anticoagulants, antiseizure medications, bisphosphonates, or calcitonin)