Surgery: Surgery is the treatment of choice for thyroid cancer. Once diagnosed, as long as conditions permit, the source and metastatic foci should be completely removed to prevent metastasis and recurrence so as to achieve a cure. This is the basic principle of surgical treatment for thyroid cancer. However, since the stage of cancer varies from early to late, the scope of surgery should also be different. Surgery must be thorough (no cancer cells are left behind or spread) and safe (no life threatening or unnecessary disability). The decision of surgery should be based on the pathological and clinical stages of thyroid cancer as well as the age and gender of the patient. Radionuclide therapy: Thyroid tissues and differentiated thyroid cancer cells have the function of 131I uptake, and the biological effect of ionizing radiation from 131I can destroy residual thyroid tissues and cancer cells to achieve the treatment purpose. For patients with differentiated thyroid cancer, 131I treatment should be performed if there is residual thyroid tissue after surgery, the 131I uptake rate is >1%, and there is residual thyroid tissue in the thyroid bed on thyroid tissue imaging. 131I treatment includes removal of residual thyroid tissue after thyroid cancer surgery and treatment of metastatic thyroid cancer lesions. Removal of residual thyroid tissue can reduce recurrence and metastatic endocrine therapy. The thyroid cancer cells of differentiated type have TSH receptors and TSH can affect the growth of thyroid cancer through its receptors. The general dose is controlled to keep the TSH level low but not to cause hyperthyroidism. Plasma T4 and TSH should be measured regularly to adjust the dose. External radiation therapy: Mainly used for undifferentiated thyroid cancer.