Chemotherapy is not necessary after breast cancer surgery. Whether breast cancer patients need chemotherapy after surgery should be determined by combining with the patient’s pathological stage and whether he/she can tolerate chemotherapy. If the patient’s pathological stage is carcinoma in situ and stage 1 breast cancer, he/she may not need chemotherapy, as well as those who have contraindications to chemotherapy such as severe allergy to chemotherapeutic drugs may not need chemotherapy either. Breast cancer refers to the phenomenon that breast epithelial cells proliferate out of control under the action of various carcinogenic factors. Chemotherapy is a method to kill tumor cells through systemic or local use of chemical drugs, which can effectively control tumor growth or kill the tumor. The principle of breast cancer treatment is to combine multiple therapies according to the biological behavior of the tumor and the physical condition of the patient, taking into account the local and systemic therapies, in order to improve the therapeutic efficacy and the quality of life of the patient. It is recommended that when a patient suffers from breast cancer, he/she should be treated under the guidance of a doctor in time, and should follow the doctor’s advice on whether or not to carry out chemotherapy after surgery, and should maintain an optimistic mindset and actively cooperate with the doctor during the period of treatment.