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