More than 100 years ago, doctors believed that breast cancer metastases by anatomical pathways, i.e., first along the lymph nodes and finally bloodstream metastases, and therefore can be cured by removing the breast and the corresponding lymphatic tissues, so the classical radical breast cancer surgery included the removal of the breast and most of the skin on its surface, the large and small chest muscles, and the whole lymphatic fatty tissue in the axilla. This approach did improve the long-term survival rate of patients at that time, and later on, based on this theory, extended radical surgery and super radical surgery emerged. It has been observed that this type of surgery has brought both physical and psychological trauma while improving the survival rate of patients, and the survival rate is not higher when the extent of resection is larger. Doctors found that distant metastasis was the root cause of cancer, and that some patients without lymph node metastasis could also develop distant metastasis. Therefore, in the 1970s, after a lot of clinical observation and research, doctors concluded that breast cancer is also a systemic disease, and the emphasis on extensive local excision of tissues does not necessarily improve the cure rate, and for some suitable patients, extensive local excision of the mass with axillary lymphatic dissection and postoperative whole breast irradiation (also commonly known as breast-conserving surgery) can achieve the same results as traditional radical surgery. The results are the same as those of conventional radical surgery. This allows a significant percentage of breast cancer patients to preserve their breasts, allowing them to treat their disease while maintaining their feminine curves and inner confidence.