Statement: Patients must have a confirmed Postmenopausal status, defined as a lack of menses for over a year, if they are to take part in the primary trial.
Primary_evidence: Inclusion Criteria:   Histologically-confirmed operable ER+ and/or PR+ invasive breast cancer or ductal carcinoma in situ (DCIS), who undergo core needle biopsy followed by surgical excision at least 2 weeks after enrollment   Postmenopausal status defined as cessation of menses for >1 year or FSH > 20 mIU/mL (within the past month)   Age  21 years   No prior chemotherapy, radiation therapy, or surgery within 6 months of study entry   Signed informed consent Exclusion Criteria:   Treatment with other investigational drugs within 6 months of study entry   Other serious intercurrent medical illness