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 Invasive Ductal Breast Carcinoma Invasive Lobular Breast Carcinoma Recurrent Breast Cancer Stage II Breast Cancer Stage IIIA Breast Cancer Stage IIIB Breast Cancer Stage IIIC Breast Cancer Female ≥18 years of age 2. Eastern Cooperative Oncology Group (ECOG) performance status 0-2 3. Postmenopausal, verified by post bilateral surgical oophorectomy or no spontaneous menses ≥ 1 year or no menses for < 1 year with follicle-stimulating hormone (FSH) and estradiol levels in postmenopausal range, according to institutional standards 4. Pathologic confirmation of invasive breast cancer diagnosed by core needle biopsy 5. Clinical T2-T4c, any N, M0 invasive breast cancer, by AJCC 7th edition clinical staging, with the goal being surgery to complete excision of the tumor in the breast and the lymph node. Primary tumor must be palpable its largest diameters is at least 2.0 cm by physical examination or by radiological assessment Note Patients with contralateral ductal carcinoma in situ and/or invasive breast cancer are not eligible Patients with multi-centric breast cancer (defined as more than one lesion is invasive breast cancer in the same breast separated by ≥ 2 cm of normal breast tissue are not eligible. 6. Invasive breast cancer is estrogen receptor positive with an Allred score of 6, 7 or 8 by local institution standard protocol. If an Allred Score is not reported on the diagnostic pathology report, ER positivity in > 66% cells is eligible. If ER positivity is ≤ 66%, the staining intensity (weak, intermediate, strong) is needed to calculate the Allred Score to determine eligibility. 7. Invasive breast cancer is Human Epidermal Growth Factor Receptor 2 (HER2) A patient is considered to have HER2 negative breast cancer if one of the following applies or 1+ by immunohistochemistry (IHC) and ISH not done  Premenopausal status 2. 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). 3. An excisional biopsy of this breast cancer. 4. Hormone replacement therapy of any type, megestrol acetate, or raloxifene within one week prior to registration. 5. Tumor estrogen receptor (ER) Allred score between 0-5 or HER2 positive by IHC (3+) or amplified by FISH > 2.0. 6. Surgical axillary staging procedure prior to study entry. Note: Fine needle aspiration (FNA) or core needle biopsy of axillary node is permitted. 7. Clinical or radiographic evidence of metastatic disease. Metastatic workup is not required, but is recommended for patients with clinical stage III disease. Note: Isolated ipsilateral supraclavicular node involvement is permitted. 8. Breast implants are contraindicated only if the implant precludes the required research biopsies or interferes with palpating the breast lesion. 9. Treatment for this cancer including surgery, radiation therapy, chemotherapy, biotherapy, hormonal therapy or investigational agent prior to study entry. 10. History of invasive breast cancer or contralateral DCIS