Early and middle stage of breast cancer refers to the stage of breast cancer. Early and middle stage of breast cancer indicates that the patient still has the chance to have the tumor surgically removed. Breast cancer can be generally categorized into stage Ⅰ, stage Ⅱ, stage Ⅲ and stage Ⅳ. Stage I refers to breast cancer with tumor diameter less than 2cm, no regional lymph node metastasis and no distant metastasis. Stage II refers to breast cancer with tumor diameter less than 2cm, lymph node metastasis and no distant metastasis, or breast cancer with tumor diameter greater than 2cm and less than 5cm, no lymph node metastasis and no distant metastasis. Generally, stage I and II breast cancer belongs to the early and middle stage. Early and middle stage breast cancer can be treated with surgery to remove the tumor and clear the lymph nodes, and after surgery, radiotherapy can be used to kill the cancer cells; endocrine therapy can also be used to stop the growth of the cancer cells by blocking the hormones, such as tamoxifen, toremifene, anastrozole, exemestane, etc; trastuzumab, patuximab, etc. can also be used to carry out targeted therapy. If diagnosed with early or middle stage breast cancer, it is recommended to consult a doctor in time to find out the cause and follow the doctor’s instructions for treatment.