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 HER2 Positive Breast Carcinoma HER2/Neu Negative Progesterone Receptor Positive Recurrent Breast Carcinoma Stage IIIB Breast Cancer AJCC v7 Stage IIIC Breast Cancer AJCC v7 Stage IV Breast Cancer AJCC v6 and v7 Histologic, pathologic or cytologic diagnosis of cancer of the female breast in either primary or metastatic setting; histological documentation of metastatic/recurrent disease is not required if there is unequivocal clinical evidence for recurrence Stage IV breast cancer (using American Joint Committee on Cancer [AJCC] 6th edition), or locally advanced (stage III) breast cancer not considered amenable to curative therapy Patients with symptomatic brain metastases or other symptomatic central nervous system (CNS) metastases are not eligible for the study; no screening studies are required among asymptomatic patients; patients with previously treated brain metastases, who are free of symptoms referable to CNS disease and who are > 3 months from treatment for brain metastases are eligible Tumors (as determined on pathology from either primary or metastatic sites) must be potentially sensitive to endocrine therapy, defined as expressing estrogen receptor (ER) and/or progesterone receptor (PgR) as determined immunohistochemical methods according to the local institution's standard protocol, >= 1% cells will be considered to be positive The protocol has been amended to permit tumors with any HER2 status, though a determination of HER2 status must have been made; patients will be considered to be eligible if HER2 expression is documented by one of the following methods Immunohistochemistry (IHC) 0 (i.e., negative), 1+, 2+, or 3+ levels of expression, or Gene amplification (fluorescent in situ hybridization [FISH]) positive or negative Patients must have at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as >= 2.0 cm with conventional techniques or as >= 1.0 cm with spiral computed tomography (CT) scan Exception: Patients with lytic or blastic bone metastases as their only site of disease will be eligible for the study even though these patients are not considered to have measurable disease by Response Evaluation in Solid Tumors (RECIST) criteria; these patients will be evaluable for time to progression, but not response Patients with all other lesions, including small lesions (longest diameter < 2.0 cm with conventional techniques or < 1.0 cm with spiral CT scan) and truly non-measurable lesions including those listed below are not eligible