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 Cancer Estrogen Receptor Positive Tumor HER2-positive Breast Cancer Histologically confirmed invasive breast cancer, with the following characteristics Early breast cancer with tumor size >1 cm (as measured by at least one of the required examination methods of clinical examination, mammography and ultrasonography) No clinical evidence of regional lymph node metastasis (via physical and/or radiological exam) (cN0) OR Clinical evidence of cN1 status, defined by nodal involvement limited to clinically or radiologically detectable metastasis to movable ipsilateral level I, II axillary lymph node(s) No evidence of metastasis (M0). 2. Postmenopausal, defined by women with Prior bilateral surgical oophorectomy; OR Amenorrhea and age ≥60 years; OR Age <60 years and amenorrhea for 12 or more consecutive months in the absence of alternative pathological or physiological cause (including chemotherapy, tamoxifen, toremifene, ovarian suppression, or hormonally-based contraception) plus FSH and serum estradiol levels within the laboratory's reference ranges for postmenopausal women 3. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 4. Primary tumor must have positive estrogen receptor (ER) ≥10% 5. Primary tumor must be HER2-positive (by IHC and/or ISH) 6. Baseline LVEF ≥55% measured by Echocardiography (preferred) or MUGA scan 7. Normal hematologic status Absolute neutrophil count ≥1500/mm3 (1.5 × 109/L) Platelets ≥100 × 109/L  Tumor of any size with direct extension to the chest wall and/or to the skin (ulceration or skin nodules) (T4 according to AJCC 8th edition cancer staging TNM) 2. Inflammatory breast cancer 3. Bilateral invasive breast cancer 4. Received any prior treatment for primary invasive breast cancer 5. Any active tumor of non-breast-cancer histology 6. Any of the following in the previous 6 months: myocardial infarction, severe/unstable angina pectoris, ongoing cardiac dysrhythmias of NCI CTCAE grade ≥2, atrial fibrillation of any grade, coronary/peripheral artery bypass graft, symptomatic congestive heart failure (NYHA functional classification ≥II), cerebrovascular accident including transient ischemic attack, or symptomatic pulmonary embolism. 7. Concurrent disease or condition that would make the subject inappropriate for study participation or any serious medical disorder that would interfere with the subject's safety 8. Contraindications or known hypersensitivity to any of the trial medications or excipients 9. Treatment with any investigational agents within 30 days prior to expected start of trial treatment 10. Any GI disorder that may affect absorption of oral medications, such as malabsorption syndrome or status post major bowel resection 11. Evidence via physical and/or radiological exam of cN2 or cN3 nodal involvement defined by: metastasis to ipsilateral level I, II axillary lymph nodes that are clinically fixed or matted, OR involvement of ipsilateral infraclavicular, internal mammary and/or supraclavicular lymph node(s) 12. History of extensive disseminated/bilateral or known presence of interstitial fibrosis or interstitial lung disease, including a history of pneumonitis, hypersensitivity pneumonitis, interstitial pneumonia, obliterative bronchiolitis, and pulmonary fibrosis. A history of prior radiation pneumonitis is not considered an criterion