Letrozole in Treating Postmenopausal Women with Ductal Carcinoma in Situ

Inclusion Criteria

• Pathologic confirmation of DCIS of the female breast without invasive cancer, 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 * Patients with microinvasion on diagnostic core biopsy, defined as tumor =< 1mm in greatest dimension, will be allowed to participate * All patients must have a clip placed, either at the time of the diagnostic biopsy or at the time of the baseline MRI prior to the start of treatment
• Patient has diagnostic tissue available for correlative studies
• Clinical stage Tis or T1mi N0 M0
• DCIS must express estrogen and/or progesterone 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
• 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) * The use of gonadotropin-releasing hormone (GnRH) analogues to achieve postmenopausal status is not allowed
• No prior surgical excision in the index breast for current DCIS diagnosis of DCIS
• Any exogenous hormone therapy must be completed 4 weeks prior to registration
• Any patients with a history of tamoxifen or raloxifene use within two years of current DCIS diagnosis are not eligible
• No prior neoadjuvant/adjuvant therapy for DCIS diagnosis
• No contraindications to breast MRI
• Measurable disease * Mammographic extent of calcifications must be accurately measurable in at least one dimension with each lesion >= 1 cm and =< 7 cm * DCIS must be visible on MRI based on central review * Patients with palpable DCIS or adenopathy are not eligible to participate * Patients with multifocal or bilateral disease are eligible
• Women diagnosed with osteoporosis may participate in this trial provided they are receiving appropriate therapy or if they have declined therapy
• Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
• Not pregnant or nursing
• Absolute neutrophil count (ANC) >= 1,000/uL
• Platelet count >= 100,000/uL
• Serum creatinine =< 1.7 mg/dL
• Bilirubin =< 2.0 mg/dL
• Aspartate aminotransferase (AST)/ alanine aminotransferase (ALT) =< 2.5 x upper limit of normal (ULN)
• Serum estradiol level assay (required for patients < 55 years of age and one year or more of amenorrhea) < 20 pg/mL