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): 18.0-65.0,  Breast Cancer Female breast cancer patients at the age of >= 18 years and <= 65 years who received first treatment； 2. Pathologically confirmed HER2-positive invasive breast cancer（which is defined as the immunohistochemistry score of > 10% immunoreactive cells being 3+ or in situ hybridization results showing HER2 gene amplification），regardless of hormone receptor status (ER and PR)； 3. According to the 2019 CSCO BC guidelines: When HER-2 positive is used as the standard for preoperative neoadjuvant therapy for breast cancer, the tumor is larger than 2 cm； 4. The Eastern Tumor Collaborative Group (ECOG) has a physical status score of ≤1； 5. The functional level of the main organs must meet the following requirements ： 1) blood routine test: hemoglobin (Hb) ≥ 90g/L;Neutrophils (ANC) ≥ 1.5 × 10^9/L; platelet count (PLT) ≥ 90 × 10^9/L; 2) Blood biochemistry: Total bilirubin (TBIL) ≤ 1.5 upper limit of normal value (ULN); Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 1.5 × ULN; alkaline phosphatase ≤ 2.5 × ULN; Urea nitrogen (BUN) and creatinine (Cr) ≤ 1.5 × ULN; 3) Heart color ultrasound: Left ventricular ejection fraction (LVEF) ≥ 55%; 6. Women of childbearing age, tested negative for serum pregnancy test 7 days before randomization，and willing to use appropriate methods during the trial and within 8 weeks after the last administration of the test drug; 7. A volunteer to participate in the study; provision of written informed consent; good compliance and willing to cooperate during the follow-up  Known history of hypersensitivity to pyrotinib or any of it components; 2. Patients have previously received antitumor treatment or radiation therapy for any malignant tumor (except for cervical carcinoma in situ and basal cell carcinoma that have been cured); 3. Patients underwent major breast cancer-free surgery within 4 weeks and have not fully recovered; 4. Subjects that are unable to swallow tablets,intestinal obstruction or dysfunction of gastrointestinal absorption; 5. Patients with severe heart disease or discomfort who cannot be treated; 6. The patient suffers from mental illness or psychotropic substance abuse and cannot cooperate; 7. Pregnant or lactating women; 8. Less than 4 weeks from the last clinical trial; 9. Patients participating in other clinical trials at the same time 10. The researchers think inappropriate