Fulvestrant or Tamoxifen in Treating Postmenopausal Women Who Are Undergoing Surgery for Ductal Carcinoma in Situ of the Breast

DISEASE CHARACTERISTICS: * Histologically confirmed ductal carcinoma in situ (DCIS) of the breast * T0 disease * Newly diagnosed disease by minimally invasive biopsy (e.g., a vacuum-assisted large core tool \[mammotome\] or an equivalent method) * Biopsy tissue available for molecular marker analysis * Baseline mammography performed within the past 8 weeks * Hormone receptor status: * Not specified PATIENT CHARACTERISTICS: Age * Postmenopausal Sex * Female Menopausal status * Postmenopausal, as defined by 1 of the following: * Age ≥ 60 * Age ≥ 45 AND amenorrheic for \> 1 year with uterus intact * Underwent bilateral oophorectomy * Follicle-stimulating hormone and estradiol levels in postmenopausal range Performance status * SWOG 0-1 Life expectancy * Not specified Hematopoietic * Absolute granulocyte count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Hemoglobin ≥ 8.0 g/dL Hepatic * SGOT and/or SGPT ≤ 2.5 times upper limit of normal (ULN) * Alkaline phosphatase ≤ 2.5 times ULN * Bilirubin ≤ 2.0 times ULN Renal * Creatinine ≤ 2.0 mg/dL Cardiovascular * No history of deep vein thrombosis Pulmonary * No history of pulmonary embolism Other * Negative pregnancy test (if clinically indicated) * No peripheral neuropathy \> grade 1 * No underlying medical, psychiatric, or social condition that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * Not specified Endocrine therapy * More than 6 months since prior hormonal therapy, including any of the following: * Antiestrogens * Estrogen * Selective estrogen-receptor modulators * Progestins * Aromatase inhibitors Radiotherapy * Not specified Surgery * Not specified Other * No prior therapy for DCIS