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,  Breast Cancer Patients must have histologically confirmed invasive carcinoma of the female breast, with 0-3 positive axillary lymph nodes Patients must have 0-3 positive axillary lymph nodes to be eligible for this study; patients with node-negative breast cancer should have sufficiently "high risk" disease to warrant chemotherapy; as general guidelines, node-negative patients with tumors of >= 1 cm or estrogen or progesterone receptor negative tumors of any size may be eligible; ultimately though, the definition of "high risk" may be determined by the treating physician, and if the treating physician feels the patient warrants chemotherapy, the patient is eligible; for patients with 1-3 positive axillary nodes, the patient is eligible regardless of primary breast tumor characteristics, if in the opinion of the treating physician, chemotherapy is deemed potentially beneficial to the patient If the patient has had a negative sentinel node biopsy, then no further axillary dissection is required, and the patient is determined to be node-negative; if an axillary dissection, without a sentinel node biopsy, is performed to determine nodal status, at least six axillary lymph nodes must be removed and analyzed and negative for the patient to be considered node-negative; axillary nodes with single cells or tumor clusters =< 0.2 mm by either hematoxylin and eosin stain (H&E) or immunohistochemistry (IHC), will be considered node-negative; lymph nodes positive for polymerase chain reaction (PCR) with tumor cells/clusters =< 0.2 mm will be considered node-negative; any axillary lymph node with tumor clusters > 0.2 mm will be considered positive If the patient has a sentinel node biopsy and one of the sentinel nodes is positive, as defined by tumor clusters > 0.2 mm, an axillary dissection must be performed; a total of at least 6 axillary lymph nodes, including sentinel nodes plus the subsequent dissection, must be removed for the patient to be eligible; of all the lymph nodes removed from both the sentinel node procedure and the axillary dissection, 1-3 must be positive for the patient to be eligible as a node-positive patient; if an axillary dissection is done without a sentinel node procedure, at least 6 lymph nodes must be removed and a 1-3 nodes must be positive for the patient to be considered node-positive and eligible for this study Determination of involvement of axillary nodes with metastatic cancer will follow the revised tumor-node-metastasis (TNM) staging system: axillary nodes with single cells with tumor clusters =< 0.2 mm, by either H&E or immunohistochemistry (IHC), will be considered negative axillary node; lymph nodes positive for PCR with tumor cells/clusters < 0.2 mm will be considered negative axillary node; any axillary lymph node with clusters > 0.2 mm will be considered to be positive Patients with estrogen-receptor and/or progesterone receptor negative, positive, or unknown tumors are eligible; estrogen-receptor (ER) and progesterone receptor (PgR) assays should be performed by immunohistochemical methods according to the local institution's standard protocol Patients with human epidermal growth factor receptor 2 (HER2) positive, negative or unknown disease are eligible for this trial; patients whose tumors are HER2 positive by either immunohistochemistry 3+ staining or demonstrate gene amplification by fluorescence in situ hybridization (FISH) may receive trastuzumab There must be negative tumor margins for invasive cancer and ductal carcinoma in situ (DCIS) in the case of mastectomy or lumpectomy; lobular carcinoma in situ (LCIS) is acceptable at the margin Patients with multi-centric breast cancer are eligible as long as all known disease is resected with negative margins, and have 0-3 positive axillary lymph nodes Patients must be registered within 84 days of the last breast surgery; patients must have undergone either modified radical mastectomy or lumpectomy; for patients undergoing sentinel node sampling or axillary dissection a simple mastectomy is acceptable; lumpectomy patients must receive radiation therapy; for patients treated with radiation therapy prior to chemotherapy, the patients should be registered on this study after the conclusion of radiation, with chemotherapy administration beginning within 7 days of registration * All primary breast and axillary node surgery must be completed prior to enrollment on study