Patient description: The patient is a 42 year-old postmenopausal woman who had a screening sonogram which revealed an abnormality in the right breast. She had no palpable masses on breast exam. Core biopsy was done and revealed a 1.8 cm infiltrating ductal breast carcinoma in the left upper outer quadrant. Lumpectomy was done and the surgical margins were clear. The tumor was HER2-positive and ER/PR negative. Axillary sampling revealed 1 positive lymph node out of 12 sampled. CXR was unremarkable. She is using “well women” multivitamins daily and no other medication. She smokes frequently and consumes alcohol occasionally. She is in a relation with only one partner and has a history of 3 pregnancies and live births. She breastfed all three children.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Estrogen Receptor-positive Breast Cancer HER2-negative Breast Cancer Stage II Breast Cancer Stage IIIA Breast Cancer Stage IIIB Breast Cancer Stage IIIC Breast Cancer Patient must have histological or cytological confirmed invasive breast cancer Patient must be premenopausal confirmed by serum estradiol level in the premenopausal range (> 25 pg/ml) at the beginning of the study; for women on oral contraceptives, these agents must be held for two weeks before the estradiol assessment is made Patient must have a negative serum pregnancy test within 7 days of registration Patient's tumor must be ER+ with or without concomitant progesterone receptor-positive (PR+) with an Allred score of 6, 7 or 8; patients with > 66.6% of cells staining positive by conventional immunohistochemistry (IHC) have a minimum Allred score of 6 and are eligible Patient's tumors must be HER2 negative by local laboratory assessment: HER2 IHC 0, 1+, or 2+ with subsequent negative fluorescent in situ hybridization (FISH) (ratio < 1.8); negative FISH alone in absence of IHC is acceptable Patient must have T2-T4c, any N, M0 breast cancer, by clinical staging (physical examination) Patient's primary tumor must be palpable and measure > 2 cm by tape, ruler or caliper measurements in at least one dimension Patient must have mammogram and ultrasound of the breast within 42 days prior to registration; if a patient has clinically palpable or suspicious nodes, then an ultrasound of the axilla is also required Patient, as documented by the treating physician, must be clinically staged as one of the following T4 a-c for which modified radical mastectomy with negative margins is the goal  Patient must not have inflammatory breast cancer defined as clinically significant erythema of the breast and/or documented dermal lymphatic invasion (not direct skin invasion by tumor or peau d'orange without erythema) Patient must not have had prior treatment for invasive breast cancer, including radiation, endocrine therapy, chemotherapy, or investigational agent; patients whose diagnosis was established by incision biopsy are not eligible Patient must not have had prior DCIS in the ipsilateral breast Patient must not have used tamoxifen for prior contralateral DCIS Patient must not have any evidence of distant metastasis (M1) on imaging; staging scans are not mandatory but any exams performed as standard of care throughout the study period will be collected for correlation as needed If patient does not agree to undergo mastectomy or lumpectomy after neoadjuvant therapy, she is ineligible for this study Patient must not be receiving other investigational agents or be enrolled in another neoadjuvant clinical trial for treatment of the existing breast cancer Pregnant and/or breastfeeding women are excluded from this study Patient must not have any concurrent life threatening illnesses Patient must not have undergone prior sentinel lymph node surgery; cores or FNA of lymph node are acceptable