Thyroid cancer is the most common malignant tumor of the thyroid gland, accounting for about 1% of all malignant tumors in the body. Papillary carcinoma accounts for 60% of thyroid cancer in adults and all of thyroid cancer in children. It is mostly seen in young women, with low malignancy, 80% of which are multicentric, with early lymph node metastasis and better prognosis. Follicular adenocarcinoma, accounting for about 20%, is common in middle-aged people and is moderately malignant, with a tendency to vascular invasion. 3.Undifferentiated carcinoma, accounting for 15%, is mostly seen in the elderly. About 50% of them have lymph node metastasis in early stage, highly malignant, and the one-year survival rate is only 5-15%. 4.Medullary carcinoma, accounting for about 15%, may have lymphatic and blood metastasis. The prognosis is not as good as papillary carcinoma, but better than undifferentiated carcinoma.