This is a randomised, double-blind multicenter Phase III study for evaluating the efficacy and safety of pyrotinib in women with early stage high-risk breast cancer after adjuvant trastuzumab. The main purpose of this study is to investigate whether pyrotinib can further reduce the risk of recurrence from previously diagnosed HER-2 positive breast cancer after adjuvant treatment with trastuzumab.

Inclusion Criteria:

• Female patients, 18 years ≤ age ≤ 75 years；
• Performance Status- Eastern Cooperative Oncology Group (ECOG) 0-1
• Histologically confirmed invasive HER2 positive breast cancer.
• Known hormone receptor status.
• Cardiovascular: Baseline left ventricular ejection fraction (LVEF)≥55% measured by Echocardiogram.
• Been treated for early breast cancer with standard of care duration of trastuzumab.
• If been not treated neoadjuvantly, lymph node metastases need to be confirmed by postoperative pathology; if been treated neoadjuvantly , have not reached totally pathologic complete response.
• Signed informed consent form (ICF) .

Exclusion Criteria:

• Positive clinical and radiologic assessments for local or regional recurrence of disease at the time of study entry.
• History of heart disease.
• Bilateral breast cancer.
• Corrected QT (QTc) interval ≥0.47 seconds.
• History of gastrointestinal disease with diarrhea as the major symptom.