There are strict indications for postoperative chemotherapy for breast cancer, and not all patients do chemotherapy. The indications for chemotherapy for breast cancer are: 1) tumor >2cm; 2) examination shows receptor negative, ER, PR negative, Her-2 positive; 3) pathological tissue grading grade is high and undifferentiated and hypodifferentiated cells are found. Patients with any of the above risk factors need to do chemotherapy treatment. Breast cancer is a systemic disease caused by genetic mutation. The purpose of chemotherapy is to destroy potential cancer cells in the blood, reduce the chance of metastasis and improve the survival rate of patients.