This is a prospective, open label, single-arm study to evaluate the efficacy and safety of neoadjuvant pyrotinib in HER2+ breast cancer patients

Inclusion Criteria:

1. Female breast cancer patients at the age of >= 18 years and <= 70 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.

Exclusion Criteria:

1. 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.