Thyroid cancer is the most common malignant tumor of the human endocrine system and one of the most rapidly increasing human malignancies in recent years, accounting for about 1% of all malignant tumors in the body. The incidence rate is increasing year by year. The pathological classification of thyroid cancer is papillary carcinoma, follicular carcinoma, medullary carcinoma and undifferentiated carcinoma. Papillary and follicular carcinomas, also known as differentiated thyroid cancer, account for about 90% of all thyroid cancers. Papillary carcinoma is the most common, followed by follicular carcinoma and medullary carcinoma. Undifferentiated carcinoma is rare and occurs mostly in older patients. The treatment of thyroid cancer is mainly surgical. For patients with advanced or distant metastases, comprehensive treatment is often used, supplemented by radiotherapy and chemotherapy after surgery. With the application of radionuclide iodine therapy technology, radiotherapy for thyroid cancer has gradually become an important treatment and adjuvant therapy. 1.Surgical treatment of primary lesion The surgical treatment of thyroid cancer is divided into primary lesion and lateral neck area treatment. Since the rate of lymph node metastasis in the central region can be as high as 50% or more, lymph nodes in the central region are usually cleared at the same time as lobectomy. Radiotherapy for thyroid cancer There are two types of radiotherapy for thyroid cancer: radioactive iodine internal irradiation (RAI) and external radiation therapy (EBRT), and the choice of radiotherapy depends on the pathological type of thyroid cancer and surgery. (1) RAI: 1131 treatment is currently the international treatment of choice for differentiated thyroid cancer after surgery and is suitable for well differentiated papillary and follicular carcinoma. Because the above two pathological types of thyroid cancer have highly concentrated absorption of 1131, 1131 treatment is feasible for their postoperative microscopic residual or recurrent metastases. RAI is not recommended in the following cases: single focal diameter <25px and no other risk factors; multifocal diameter <25px and no other risk factors. (2) EBRT: The indications for extracorporeal radiotherapy are summarized as follows: ① Postoperative radiotherapy should be routinely performed for undifferentiated thyroid cancer, or simple palliative radiotherapy if surgical resection is not possible. The indications for radiotherapy for differentiated thyroid cancer include: those with unclear surgical margins or residual cancer, especially those who do not take I131; those who are considered by surgeons to be at high risk of local recurrence; those with large residual lesions after surgery, which absorb I131 but are not sufficient to reach the therapeutic dose; those who cannot be resected after surgery or recur after I131 treatment; those with extensive lymph node metastases, especially those with invasion of the envelope. The target area of differentiated thyroid cancer must cover the preoperative tumor area, postoperative tumor bed, tracheoesophagus above the bulge and anterior mediastinum, and the recommended irradiation dose is 60~66Gy. For undifferentiated thyroid cancer, the recommended dose is ≥65Gy. 3. Chemotherapy and molecular targeted therapy for thyroid cancer Generally speaking, thyroid cancer is not sensitive to In general, thyroid cancer is not sensitive to chemotherapy, especially differentiated thyroid cancer. However, chemotherapy can be used for patients with undifferentiated carcinoma or inoperable carcinoma. The main drugs used are adriamycin or epiamycin, platinum agents, 5-Fu and other drugs. About molecular targeted therapy for thyroid cancer is still in the exploration stage, some drugs have entered phase II and phase III clinical trials, and molecular targeted therapy is expected to be one of the development directions of thyroid cancer treatment.