1. Regulation of thyroid function After surgical removal of one side or the whole thyroid gland, thyroxine should be routinely supplemented to keep thyroid function as normal as possible. For differentiated thyroid cancer, long-term supplementation of thyroxine can inhibit the secretion of TSH, reduce the possibility of tumor recurrence and significantly improve the prognosis of patients. Therefore, the level of TSH should be closely monitored during the follow-up process, and it is best to maintain it below the normal value, while other indicators are within the normal range. 2. Timely detection and management of tumor recurrence and metastasis After thyroid cancer surgery, regular review should be conducted to detect possible local recurrence or metastasis, including lymph node metastasis in the neck and upper mediastinum and distant metastasis, such as lung, bone and brain metastasis. It is generally recommended to review regularly at 3 months, 6 months and 1 year after surgery, and every 6 months after 1 year. The examination methods include routine physical examination, thyroid and neck ultrasound, CT, MRI, isotope examination, chest X-ray, etc. If suspicious nodules are found, cytological or pathological examination is performed if necessary to clarify the nature. For example, in patients with differentiated thyroid cancer who have undergone total thyroidectomy, a significant increase in TG (thyroglobulin) indicates the possibility of tumor recurrence; in patients with medullary carcinoma, a significant increase in serum calcitonin level also indicates tumor recurrence or metastasis. If local recurrence or lymph node metastasis in the neck or upper mediastinum is detected, most patients can still achieve radical treatment through reoperation. For differentiated thyroid cancer, if lung metastasis occurs, all residual thyroid glands can be removed and all metastatic lymph nodes can be cleared, and then 131I isotope therapy can be performed, which can also achieve better results. For distant metastases in bone and brain, the metastases can sometimes be removed first and then treated with isotope therapy. If surgical resection is not possible, the treatment is the same as pulmonary metastases. It is especially important to remind that radiotherapy and chemotherapy are not recommended after surgery for differentiated thyroid cancer and medullary carcinoma that can be excised surgically. Because radiotherapy and chemotherapy cannot bring higher cure rate and control rate, on the contrary, they will bring more side effects and complications. Only for patients who only have a small amount of tumor left after surgery, postoperative radiotherapy can improve the control rate and prognosis. For patients with undifferentiated thyroid cancer, tumor recurrence or metastasis may occur within a short period of time, so the interval of follow-up should be reduced, for example, once every 1 month. Once the tumor is found to recur or metastasize, it indicates a poor prognosis and the tumor tends to grow rapidly. Most patients lose the chance of re-operation and can only be managed symptomatically or controlled by radiotherapy or chemotherapy. The only work that surgery can do may be tracheotomy or tracheostomy to solve the ventilation and gastrostomy to solve the feeding problem.