Patient description: The patient is a 45-year-old postmenopausal woman with cytologically confirmed breast cancer. A core biopsy revealed a 3 cm invasive ductal breast carcinoma in the left upper outer quadrant. The tumor is HER2-positive and ER/PR negative. Axillary sampling revealed 5 positive lymph nodes. CXR was remarkable for metastatic lesions. The patient is using multivitamins and iron supplements. She does not smoke or consume alcohol. She is not sexually active and has no children. She is a candidate for tumor resection and agrees to do so prior to chemotherapy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Breast Ductal Carcinoma In Situ Invasive Breast Carcinoma Multicentric Breast Carcinoma Multifocal Breast Carcinoma Synchronous Bilateral Breast Carcinoma Patients must have a histologically confirmed diagnosis of node positive (1-3 nodes) invasive breast carcinoma with positive estrogen and/or progesterone receptor status, and negative HER-2 status; estrogen and progesterone receptor positivity must be assessed according to American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines as either estrogen receptor (ER) or progesterone receptor (PR) >= 1% positive nuclear staining; HER-2 test result negativity must be assessed as per ASCO/CAP 2013 guidelines using immunohistochemistry (IHC), in situ hybridization (ISH) or both; HER-2 is negative if a single test (or all tests) performed in a tumor specimen show: a) IHC negative (0 or 1+) or b) ISH negative using single probe or dual probe (average HER-2 copy number < 4.0 signals per cell by single probe or HER-2/CEP ration < 2.0 with an average copy number < 4.0 signals per cell by dual probe); if HER-2 IHC is 2+, evaluation for gene amplification (ISH) must be performed and the ISH must be negative; ISH is not required if IHC is 0 or 1+; HER-2 equivocal is not eligible Patients with multifocal, multicentric and synchronous bilateral breast cancers are allowed Multifocal disease is defined as more than one invasive cancer < 2 cm from the largest lesion within the same breast quadrant; (NOTE: the Oncotype DX testing must be completed on the largest lesion) Multicentric disease is defined as more than one invasive cancer >= 2 cm from the largest lesion within the same breast quadrant or more than one lesion in different quadrants (NOTE: Oncotype DX testing should be completed on all tumors and the determination for should be made on the highest recurrence score) Synchronous bilateral disease is defined as invasive breast cancer with positive lymph nodes (axillary or intramammary) in at least one breast, diagnosed within 30 days of each other; (NOTE: the Oncotype DX testing should be completed on both tumors and the tumor with the highest recurrence score should be used) Patients will have undergone axillary staging by sentinel node biopsy or axillary lymph nodes dissection (ALND); patients must have at least one, but no more than three known positive lymph nodes (pN1a, pN1b or pN1c); patients with micrometastases as the only nodal involvement (pN1mi) are not eligible; patients with positive sentinel node are not required to undergo full axillary lymph node dissection; this is at the discretion of the treating physician; axillary node evaluation is to be performed per the standard of care at each institution Patients must not have inflammatory breast cancer and must not have metastatic disease Patients with a prior diagnosis of contralateral ductal carcinoma in situ (DCIS) are eligible if they underwent a mastectomy or lumpectomy with whole breast radiation; prior partial breast irradiation, including brachytherapy, is not allowed; patients with a prior diagnosis of ipsilateral DCIS or invasive breast cancer who received radiation to that breast are not eligible Patients must have had either breast-conserving surgery with planned radiation therapy or total mastectomy (with or without planned postmastectomy radiation); patients must have clear margins from both invasive breast cancer and DCIS (as per local institutional guidelines); lobular carcinoma in situ (LCIS) at the margins is allowed Registration of patients who have not yet undergone Oncotype DX screening must occur no later than 56 days after definitive surgery; (for all patients, Step 2 Registration must occur within 84 days after definitive surgery); if the Oncotype DX Breast Cancer Assay has not been performed, patients must be willing to submit tissue samples for testing to determine the Recurrence Score value; a representative block or unstained sections from the representative block are sent directly to Genomic Health for Oncotype DX Breast Cancer Assay which will be performed according to the standard commercial process