Modified radical mastectomy is a more common method for radical treatment of breast cancer, which mainly refers to the removal of the entire breast tissue plus axillary lymph node dissection, preserving the pectoralis major and pectoralis minor muscles. After surgery, the next treatment is decided according to the pathology, including further radiotherapy, chemotherapy, endocrine therapy and targeted drug therapy. 1. adjuvant radiotherapy is needed if the number of axillary lymph node metastasis is high. 2. in other cases, 4-6 courses of adjuvant chemotherapy are needed. 3. if estrogen and progesterone receptor positive, endocrine therapy is needed for at least 5 years. 4. HER2 positive If there is gene amplification, it can be treated with targeted drug Herceptin. Breast cancer is a systemic disease, surgery including modified radical surgery is only the first step, and a series of comprehensive treatment should follow.