Thyroid cancer is the most common malignant tumor of the thyroid gland, accounting for about 1% of all malignant tumors in the body. The most common type of thyroid cancer is papillary carcinoma, which accounts for about 70% of all adult thyroid cancers. This type of cancer is well-differentiated, slow-growing and less malignant, and can have lymph node metastasis in the neck at an early stage, but has a better prognosis. About 15% are follicular carcinomas, which have less lymph node metastasis in the neck, but develop more rapidly and are moderately malignant. Another 5%-10% of cases are undifferentiated carcinoma, mostly seen in the elderly, which develops rapidly and is highly malignant, prone to lymph node metastasis in the neck or invasion of trachea and esophagus or even distant metastasis, with poor prognosis. Medullary carcinoma, a rare type of cancer, is moderately malignant and can have lymph node metastasis and distant metastasis in the neck. Although thyroid cancer is a member of the daunting “cancer” family, as long as it is detected, diagnosed and treated early, most patients can have a good prognosis and even live like normal people through standardized surgery, endocrine drugs and radionuclide therapy.