EC-TH chemotherapy regimen is a common chemotherapy regimen for adjuvant chemotherapy after breast cancer surgery, starting with 4 cycles of EC regimen. E in EC mainly refers to adriamycin-based chemotherapy drugs, and C mainly refers to cyclophosphamide. After 4 cycles of EC regimen, 4 cycles of TH regimen will be administered, T in TH mainly refers to paclitaxel-based chemotherapy drugs, such as paclitaxel and docetaxel, and H mainly refers to trastuzumab-targeted drugs, trastuzumab is mainly indicated for patients with strong HER-2 positive immunohistochemistry for breast cancer, which needs to be used for 1 year. After 4 cycles of TH chemotherapy, trastuzumab monotherapy is administered until 1 year has elapsed.