There are many different types of thyroid cancer and their clinical biology varies greatly. Low-grade malignant thyroid cancer can sometimes survive naturally for more than 10 years, and some can even survive with lung metastases for more than 5 years. However, highly malignant thyroid cancer can lead to death within a short period of time. Most thyroid cancers originate from the follicular epithelium, a few can arise from parafollicular C cells, and very few from the interstitium of the thyroid gland. In addition to primary cancer, thyroid gland can also have secondary metastatic tumors. Currently, the following classifications are mostly used at home and abroad: 1. papillary carcinoma (cryptic carcinoma, intraglandular type, extraglandular type); 2. follicular carcinoma (slight or suspicious infiltration of the envelope vessels, moderate or obvious infiltration of the envelope), including Hürthle cell carcinoma; 3. medullary carcinoma (family genetic type, disseminated type) MEN-2A or MEN-2B; 4. undifferentiated carcinoma (including squamous cell carcinoma); 5. malignant lymphoma; 6. metastatic carcinoma; 7. others. Metastatic carcinoma; 7. Others. (Note: Papillary carcinoma and follicular carcinoma are also known as differentiated thyroid cancer)