1.Therapeutic surgery Benign tumors can generally be cured as long as they can be completely removed. However, the surgical treatment of malignant tumors is more complicated, including radical surgery, palliative surgery and endocrine adenomectomy. (1) Radical surgery: It refers to the extensive resection of the primary foci of malignant tumors to achieve the purpose of “cure” as far as possible. If the tumor grows in a certain organ, it needs to be removed together with the organ or the whole organ, such as stomach cancer, lung cancer, esophageal cancer, kidney cancer and cervical cancer. Malignant tumor can infiltrate and spread to the surrounding tissues, so radical surgery should remove the primary focus and the surrounding tissues that may be involved, and the surrounding metastatic lymph nodes should also be removed together. (2) Palliative surgery: It is mainly used for patients with advanced tumor and can be divided into palliative tumor reduction surgery and palliative decompensation surgery. Palliative reduction surgery refers to when the tumor has distant metastasis or local spread, surgical removal of the primary foci or metastases to reduce the tumor load and improve the immune function of the body, so as to facilitate other treatments (such as chemotherapy, radiotherapy and immunotherapy, etc.) to play a better role to improve the efficacy or prolong the survival of patients. For example, patients with metastatic kidney cancer, who have their primary renal foci removed by surgery followed by systemic therapy (immunotherapy or targeted therapy), have better efficacy than systemic therapy alone. Palliative decompensative surgery refers to patients with tumor who cannot be surgically removed or the significance of surgical removal of tumor is no longer significant, but the surgical method can relieve direct life-threatening complications, alleviate symptoms, reduce pain and improve patients’ quality of life. For example, in advanced gastric cancer patients with gastrointestinal obstruction, gastrointestinal fistula can be performed to relieve symptoms and maintain nutrition. (3) Endocrine gland removal surgery: The occurrence and development of some tumors are related to certain hormones in the body, so the endocrine-dependent tumors can be regressed or their development can be delayed by removing the corresponding endocrine glands to achieve the purpose of treatment. In the case of metastatic prostate cancer, it is impossible to achieve radical cure through surgery, and radiotherapy and chemotherapy are not sensitive, so clinically, the testicles are removed to significantly reduce the level of androgens in the patient’s body, and the prostate cancer cells are killed by the method of “cutting off their food and grass”. Some congenital or acquired lesions may become malignant when they develop to a certain extent. If timely surgery is performed to remove the lesions, the occurrence of tumor may be prevented. The risk of malignant transformation into melanoma increases for nevi that are easily subjected to friction (such as those located under the nails or on the feet), so surgery can be considered to remove them. Congenital multiple colonic polyposis, if no surgery is done 50% of patients develop malignancy at the age of 40, and almost all patients will develop colon cancer after the age of 70, so it is better for patients to be able to do surgery before the age of 20-30. 3.Diagnostic surgery Most tumors are diagnosed and staged through physical examination by doctors, imaging examinations (X-ray, ultrasound, CT and MRI) and endoscopy, and such diagnosis and staging are called clinical diagnosis and clinical staging. However, the final diagnosis of tumor is obtained by pathological examination of tumor tissues obtained by puncture or surgery, and the surgery performed for the purpose of pathological diagnosis or pathological staging is called diagnostic surgery. Before removing organs or radiotherapy or chemotherapy, some tumors need to be removed through surgery for pathological examination to obtain pathological diagnosis and provide basis for surgery or radiotherapy or chemotherapy. 4. Restorative surgery After surgical removal of tumor tissues or organs, it may affect the function of organs or body, or damage the appearance of the body, so restorative surgery refers to the surgical reconstruction and rehabilitation of the patient’s function or improve the appearance. For example, the reconstruction of the digestive tract after radical esophageal cancer surgery restores the integrity and partial function of the digestive tract for the patient. Another example is the reconstruction of breast with rectus abdominis flap after radical breast cancer surgery, or the filling of the posterior pectoralis major muscle with silicone to perfect the shape of the breast.