Surgery is still one of the main treatment options for breast cancer. The general trend is to minimize surgical damage and to preserve the shape of the breast as much as possible for early-stage breast cancer patients when the equipment allows. Regardless of the type of surgery, the principle of radical treatment and preservation of function and appearance must be strictly followed. (I) Indications for surgery Halsted pioneered radical breast cancer surgery, which has become the standard treatment for breast cancer in the past hundred years because of its reasonable operation and clear efficacy. In the past half century, many exploratory modifications have been made to the breast cancer surgery, and the general trend has been both conservative and expanded, which are still under debate. Partial mastectomy and total mastectomy are the representative procedures for conservative surgery. After surgery, radiotherapy is required, and the radiation dose varies, generally from 30 to 70 Gy, which can be more effective for strictly selected early-stage cancers. However, it is difficult to conclude whether it is used as a routine treatment for early breast cancer and how to select such early cancer accurately and without error. (2) Contraindications to surgery 1. Systemic contraindications: ①Distant metastasis of tumor. (2) Those who are too old and weak to tolerate surgery. ③Poor general condition, presenting malignant quality. ④Those who cannot tolerate surgery due to dysfunction of important organs. 2. Contraindications for local lesions: Stage III patients with one of the following conditions: ① orange peel edema of the breast skin exceeding half of the breast area; ② satellite nodules on the breast skin; ③ breast cancer invading the chest wall; ④ enlarged parasternal lymph nodes clinically examined and confirmed to be metastases; ⑤ edema of the affected upper limbs; ⑥ supraclavicular lymph nodes pathologically confirmed to be metastases; ⑦ inflammatory breast cancer. If two of the following five conditions exist: ① tumor rupture; ② orange peel edema of the breast skin occupying less than 1/3 of the total breast area; ② fixation of the cancer tumor with the pectoralis major muscle; ④ axillary lymph nodes with a maximum diameter of more than 2.5 cm; ⑤ axillary lymph nodes adhering to each other or adhering to the skin or deep tissue. In 1894, Halsted and Meger published the surgical principles of radical surgery for breast cancer: (1) the primary focus and regional lymph nodes should be excised as a whole; (2) all breast glands and pectoralis major and minor muscles should be excised; (3) axillary lymph nodes should be excised as a whole and completely. (2) After complete separation of the flap, the pectoralis major and minor muscles should be cut from the chest wall and turned outward; (3) The axillary fossa should be dissected and the long thoracic nerve should be preserved if there are no obvious enlarged lymph nodes in the axilla; (4) All defects of the chest wall should be implanted. Common intraoperative complications include: ① Axillary vein injury: Mostly due to unclear dissection when dissecting the fat and lymphatic tissue around the axillary vein, or due to cutting the axillary vein branches too close to the axillary vein trunk. Therefore, it is very important to clearly expose and preserve a small number of branch ends. ②Pneumothorax: When cutting the rib stop of the pectoralis major and pectoralis minor, sometimes the small blood vessel penetrating branch of the chest wall is clamped too deeply and the intercostal muscle and pleura are touched, resulting in tension pneumothorax. Postoperative complications include: ① Subcutaneous effusion: mostly due to poor fixation of the skin piece or poor drainage. It can be prevented by multiple suture fixation between subcutaneous and chest wall tissues and continuous negative pressure drainage. ② Skin sheet necrosis: tight skin suture and thin skin sheet can be the cause of its occurrence. If there are more skin defects, skin implants are recommended. (③) Edema of the affected upper limb. (ii) Restricted lifting of the affected upper limb: it is mainly due to reduced postoperative activities and subcutaneous scar traction. Therefore, functional exercise should be carried out as early as possible after surgery, and the degree of free lifting should be achieved basically in about one month after surgery. 2.Expanded radical surgery for breast cancer: Expanded radical surgery for breast cancer includes radical surgery for breast cancer, i.e. radical surgery and internal breast lymph node removal, i.e. removal of 1-4 intercostal lymph nodes, in this case, the second, third and fourth rib cartilage should be removed. The former is more traumatic and has more complications, so the latter is mostly used. 3.Imitative radical surgery (modified radical surgery): mainly used for non-invasive cancer or stage I invasive cancer. Those with no obvious axillary lymph node enlargement at stage II can also be selected. (1) Type I: Preserve the pectoralis major and pectoralis minor muscles. The principles of skin incision and flap separation are the same as those of radical surgery. The whole breast is dissected to the axillary side, and then the axillary lymph nodes are removed, and the scope of removal is basically the same as that of radical surgery. The anterior thoracic diverticulum should be preserved. Finally, the whole breast and axillary lymphatic tissues are removed in whole. (2) Type II: The pectoralis major muscle is preserved and the pectoralis minor muscle is excised. The skin incision and other steps are the same as before. After the breast is dissociated to the outer edge of the pectoralis major muscle, the attachment points of the 4th, 5th and 6th ribs of the pectoralis major muscle are cut and turned upward to enlarge the operative field, and the attachment points of the pectoralis minor muscle are cut at the rostral process of the scapula, and the following steps are the same as the radical surgery, but attention should be paid to the preservation of the anterior thoracic nerve and the accompanying blood vessels. 4.Simple mastectomy: As an old procedure, it was once replaced by radical breast cancer surgery. In recent years, with the development of breast cancer biology, total mastectomy has regained importance. Its indications: Firstly, for early cases with non-invasive or axillary lymph nodes without metastasis, it can be performed without radiotherapy after surgery. Secondly, for locally more advanced breast cancer with simple excision followed by radiation therapy. If we look at the increasing cosmetic requirements, total mastectomy still requires complex breast reconstruction. It will not be suitable for early stage disease in young and middle-aged women. Therefore, its main indications should be limited to the elderly and frail or certain advanced cases where only palliative resection can be performed. 5. Less than total mastectomy: In recent years, due to the advancement of radiotherapy equipment, the discovery of lesions earlier than before and the patient’s demand for better postoperative quality of life, many conservative surgical approaches less than total mastectomy have been reported. The procedure is performed from partial excision up to l/4 mastectomy with postoperative application of radiation therapy. Breast-conserving surgery is not suitable for all cases of breast cancer and cannot replace all radical surgery, but is a modified form of breast cancer treatment and care should be taken to avoid local recurrence. Its indications are generally as follows: (1) small tumor, suitable for clinical T1 and some T2 (less than 4 cm) lesions or less; (2) peripheral type tumor, often not suitable for those located under the areola; (3) solitary lesion; (4) clear tumor boundary, often not suitable for those who cannot see clear boundary under naked eye or microscope; (5) axillary lymph nodes without clear metastasis. The effect of treatment is related to the following factors: ①the tumor must have normal border at the cut edge, if there is enough normal tissue at the cut edge, the prognosis is better; ②the size and histological grade of the primary tumor; ③postoperative radiotherapy, if no radiotherapy is done after surgery, the local recurrence rate is higher.