Thyroid cancer is the most common malignant tumor of the thyroid gland, accounting for 1% of all malignant tumors in the body. Except for medullary carcinoma, the vast majority of them originate from follicular epithelial cells. The pathological types are: 1. Papillary carcinoma. It accounts for 60% of thyroid cancer in adults and all thyroid cancers in children, with low malignancy, 80% being multicentric and about 1/3 involving bilateral thyroid glands. It appears earlier with cervical lymph node metastasis, but has a better prognosis. 2. Follicular carcinoma. It accounts for about 20%, common in middle-aged people around 50 years old, moderately malignant, with tendency to invade blood vessels, 33% can be metastasized to lung, liver, bone and nervous system, 10% of cervical lymph node invasion, prognosis is not as good as papillary carcinoma. 3.Undifferentiated carcinoma. It accounts for about 15%, mostly seen in 70 years old. It develops rapidly and about 50% have cervical lymph node metastasis in early stage, which is highly malignant. In addition to invading trachea and laryngeal nerve or esophagus, it can also metastasize to lung and bone distantly through blood transport. The prognosis is very poor. The average survival time is 3-6 months, and the one-year survival rate is only 5%-15%. 4. Medullary carcinoma. It accounts for only 7%. The cells are nested or cystic in arrangement, without papillae or follicular structures, and are undifferentiated; there are amyloid deposits in the tumor. There is amyloid deposition within the tumor. There may be cervical lymph node invasion and hematogenous metastasis. The prognosis is not as good as papillary carcinoma, but better than undifferentiated carcinoma. Clinical manifestations: A lump in the thyroid gland with hard and fixed texture and uneven surface is a common manifestation of all types of cancer. The gland has little up and down mobility during swallowing. Undifferentiated carcinoma may show the above symptoms within a short period of time. In addition to the obvious growth of the mass, it also has the characteristic of invading the surrounding tissues. In late stage, it may produce hoarseness, difficulty in breathing and swallowing, sympathetic nerve compression causing Horner syndrome and invasion of cervical plexus causing pain in ear, occiput and shoulder and local lymph node and distant organ metastasis. Cervical lymph node metastasis occurs earlier in undifferentiated carcinoma. Diagnosis: It is mainly based on clinical manifestations. If a mass is found in the thyroid gland with hard and fixed texture, uneven surface, enlarged cervical lymph nodes or with pressure symptoms, or if a thyroid mass has been found for many years and has increased rapidly in size recently, thyroid cancer should be suspected. Treatment: Surgery is the basic treatment for all types of thyroid cancer except undifferentiated carcinoma, and adjuvant treatment with nuclear hormone, thyroid hormone and external radiation. 1.Surgical treatment. It includes surgery of the thyroid gland itself and cervical lymph node dissection. 2.Endocrine treatment. Those who have total or secondary resection of thyroid cancer should take thyroxine tablets for life. 3.Radionuclide therapy. For papillary carcinoma and follicular carcinoma, postoperative application of 131 iodine is suitable for patients over 45 years old, multiple cancer foci, locally invasive tumors and distant metastases. 4.Radiation external irradiation therapy. It is mainly used for undifferentiated thyroid cancer.