Anastrozole and Letrozole After Surgery for the Treatment of Stage I-III Breast Cancer

Inclusion Criteria

• REGISTRATION-INCLUSION CRITERIA
• Disease characteristics:
• Histological confirmation of invasive breast carcinoma
• Stage I-III breast cancer
• Estrogen receptor (ER) positive disease according to American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines as ER >= 1% positive nuclear staining
• Completion of all planned cancer treatments prior to registration:
• Surgical resection of breast and nodal surgery; (NOTE: Reconstructive surgery does not have to be completed)
• Adjuvant radiation therapy, if needed
• Neoadjuvant and/or adjuvant chemotherapy, if needed
• Post-menopausal defined as
• Age >= 60 and amenorrhea > 12 consecutive months OR
• Previous bilateral oophorectomy OR
• Age 12 consecutive months and documented follicle stimulating hormone (FSH) level within post-menopausal range according to institutional standard
• NOTE: Patients who did not meet these criteria at time of diagnosis and received pre-operative (neoadjuvant) or post-operative (adjuvant) chemotherapy will not be allowed to participate
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0, 1, or 2
• Hemoglobin >= 8.0 g/dL (obtained = = 1500/mm^3 (obtained = = 70,000/mm^3 (obtained = = 1.3 pg/ml, AND
• E2 >= 0.5 pg/ml

Exclusion Criteria

• REGISTRATION-EXCLUSION CRITERIA
• Pre-menopausal women receiving ovarian function suppression (goserelin, leuprolide, etc.)
• Stage IV (metastatic) breast cancer
• HER2 positive breast cancer as defined by
• HER2 immunohistochemistry (IHC) >= 3+
• HER2/CEP17 >= 2.0
• HER2/CEP17 = 6.0 signals/cell
• Prior endocrine therapy for this breast cancer. Exceptions:
• Pre-operative aromatase therapy (anastrozole, letrozole, or exemestane) and last treatment was >= 4 weeks prior to registration OR
• Pre-operative tamoxifen therapy and last treatment was >= 12 weeks prior to registration
• Currently receiving any of the following cancer-directed therapies:
• Radiation therapy
• Systemic therapy such as chemotherapy (standard or investigational)
• Bisphosphonate therapy started = 4 weeks prior to registration. Patients not currently taking bisphosphonates will be allowed to start bisphosphonate therapy after completion of anastrozole (1 mg and 10 mg daily [if given]). Information regarding bisphosphonate therapy will be collected
• Current use of systemic or topical exogenous estrogen or progesterone (menopausal hormone replacement therapy [HRT])
• Prior ovarian function suppression (leuprolide, goserelin, etc.)
• Inability to provide informed consent
• History of contralateral ductal carcinoma in situ (DCIS) or invasive breast cancer
• NOTE: Exception allowed if
• Patient did not receive adjuvant endocrine therapy OR
• Patient received adjuvant endocrine therapy but has been off treatment for at least 6 months prior to registration
• Concurrent active malignancy or history of malignancy = = 6 months prior to registration