Thyroid cancer is the most common tumor of the endocrine system in surgery. Its incidence has been on the rise in recent years. Surgery is the only treatment available to cure thyroid cancer. Although most thyroid cancers are treated well after standardized surgery and have a long or even non-life-threatening survival, there is still a possibility of recurrence and metastasis, just like other malignant tumors in the body. Follow-up interval In principle, lifelong follow-up should be conducted, generally every three months within the second year after surgery, at least every six months from the second year to the fifth year, and at least once a year after the fifth year, but of course, if any treatment-related discomfort occurs, one should go to the hospital in time. Monitoring content Physical examination: Physical examination, including thyroid palpation and examination of lymph nodes in the neck, can detect thyroid swelling or metastatic lymph nodes in time, and is the easiest, convenient and quickest examination. Color ultrasound: Ultrasound examination is non-invasive, radiation-free and easy to operate, so it is the preferred follow-up method after thyroid cancer surgery. Ultrasound examination can detect recurrent or metastatic lesions of thyroid cancer that cannot be palpated by physical examination. Thyroid function: including T3, T4, TSH, etc. Patients with thyroid cancer often have hypothyroidism after removal of one lobe of the gland or all of them. After surgery, they need to take thyroxine tablets for a long time in order to suppress TSH and reduce its stimulating effect on tumor cells, so they need to monitor thyroid function regularly, with TSH controlled at 0.1-0.5mU/L for low-risk patients and 0.15mU/L for high-risk patients, and then adjust thyroxine according to The dosage of thyroxine tablets should then be adjusted according to the results of the tests. Thyroglobulin: Thyroglobulin is secreted by thyroid tissue and is normally released into the blood in very small amounts, with a normal value of <10 μg/L. If thyroglobulin is decreased or not measured after total thyroidectomy, an elevated thyroglobulin should alert you to tumor recurrence or metastasis. If thyroglobulin is less than 1μg/L, the chance of recurrence is very low; if it is between 1μg/L and 10μg/L, the chance of recurrence is about 20%; if it is more than 10μg/L, the chance of recurrence is more than 60%. Therefore, after total thyroidectomy, dynamic monitoring of serum thyroglobulin can predict early recurrence and metastasis. Serum calcitonin: Calcitonin is also secreted by the thyroid tissue, and the amount of calcitonin in normal human serum is very small. When medullary thyroid cancer is present, the serum calcitonin level is significantly higher than normal. After surgery to remove medullary thyroid cancer, the serum level will drop rapidly. Therefore, postoperative monitoring of serum calcitonin is an effective method to monitor the treatment effect of medullary thyroid cancer and to detect recurrent or metastatic lesions at an early stage. In addition, chest X-ray, abdominal ultrasound, cranial MRI, whole-body bone scan and PET can also help to detect distant metastases. Follow-up medication After thyroid cancer surgery, it is often necessary to take levothyroxine tablets (euthyroxine) for a long time. The dosage of thyroxine tablets should be adjusted according to the TSH level. Serum TSH values should be checked every 2 to 3 months to control TSH values between normal and mild hyperthyroidism. There are also application of some immune enhancing agents, such as thymopentin, interleukin 2, etc., to enhance the body's immune function and fight against tumors.