DISEASE CHARACTERISTICS: - Pathologic confirmation of ductal carcinoma in situ (DCIS) without invasive cancer of the female breast with diagnosis rendered on core biopsy only, completed within 60 days before registration - Patients diagnosed with DCIS on the basis of surgical biopsy are not eligible for this study - Disease stage Tis, N0, M0 - All patients must have had a diagnostic core biopsy with clip placed at time of biopsy or prior to baseline MRI - Diagnostic tissue available for correlative studies - DCIS must express estrogen receptor, as determined by immunohistochemical methods on the diagnostic pathology sample, according to the local institution's standard protocol - Greater than or equal to 1% cells will be considered to be positive - Measurable disease - Mammographic extent of calcifications must be accurately measurable in at least one dimension with each lesion ≥ 1 cm and ≤ 5 cm - DCIS must be visible on MRI without radiographic evidence of invasive cancer - Patients with palpable DCIS or adenopathy are not eligible to participate PATIENT CHARACTERISTICS: - Patients must be postmenopausal* defined as: - Age ≥ 55 years and one year or more of amenorrhea - Age < 55 years and one year or more of amenorrhea, with an estradiol assay < 20 pg/mL - Surgical menopause with bilateral oophorectomy (at least 28 days must elapse from surgery to time of study registration) NOTE: *The use of GnRH analogs to achieve postmenopausal status is not allowed. - ECOG performance status 0 or 1 - ANC ≥ 1,000/μL - Platelet count ≥ 100,000/μL - Serum creatinine ≤ 1.7 mg/dL - Bilirubin ≤ 2.0 mg/dL - AST/ALT ≤ 2.5 times upper limit of normal - Serum estradiol level assay < 20 pg/mL - Required for patients < 55 years of age and one year or more of amenorrhea - Not pregnant or nursing - No contraindications to breast MRI - Women diagnosed with osteoporosis may participate in this trial provided they are receiving appropriate therapy PRIOR CONCURRENT THERAPY: - No prior surgical excision in the index breast for ductal carcinoma in situ (DCIS) or invasive cancer - Any exogenous hormone therapy must be completed 4 weeks prior to registration - Any patients with a history of tamoxifen or raloxifene use will be excluded - No prior neoadjuvant/adjuvant therapy for breast cancer