With the significant increase in the incidence of thyroid cancer, the concern about thyroid cancer is increasing day by day. Thyroid cancer is more common in women and more prevalent in young adults. Thyroid cancer is usually divided into differentiated thyroid cancer, medullary thyroid cancer and undifferentiated thyroid cancer, among which differentiated thyroid cancer is divided into papillary thyroid cancer and follicular thyroid cancer. In addition, thyroid lymphoma, thyroid squamous cell carcinoma, metastatic carcinoma, etc. are rare. Papillary carcinoma is the most common type of thyroid cancer, accounting for 40-60%, followed by follicular carcinoma accounting for 10-15%, undifferentiated carcinoma accounting for 15%, and medullary carcinoma accounting for 5%. Compared with tumors of other organs, thyroid cancer develops slowly and a few of them even have extensive metastases in the lungs and survive for a long time. As an endocrine organ, thyroid gland can synthesize, store and secrete thyroid hormones. Thyroid hormones promote the metabolic process and maintain the normal function of organs in the human body, and are indispensable and important hormones. Normal thyroid follicular cells hardly proliferate. However, if the signals that stimulate growth are abnormally enhanced or the signals that inhibit growth are absent, growth regulation is dysregulated and can lead to tumor formation. Representative causes of such dysregulation include radiation external exposure. The findings, such as the increased incidence of thyroid cancer in children due to nuclear material leakage after the explosion of the Chernobyl nuclear power station in the former Soviet Union, show that exposure to radiation predisposes to uncontrolled cell growth. In addition, mutations in cell regulatory genes, such as familial medullary thyroid cancer or familial papillary carcinoma, can also lead to thyroid cancer. Risk factors In order to prevent the occurrence of thyroid cancer, the easiest and most effective way to prevent the development of thyroid cancer is to identify the factors associated with the development of thyroid cancer and to avoid the causes of the disease. To date, the exact cause of thyroid cancer has not been elucidated. According to the literature, the occurrence of thyroid cancer may be related to previous history of breast cancer, exposure to radiation, excessive estrogen, family history (genetic history), etc., but further research is needed to confirm. II. Main symptoms Most patients are found incidentally when they undergo ultrasound examination of the neck, while some patients are found when they visit the hospital due to a palpable mass in the neck. The presence of the following symptoms in patients with a palpable neck mass may indicate malignancy. 1.Patients who have received previous radiotherapy; 2.The swelling has increased in size in recent months; 3.The swelling presses on the trachea and esophagus, causing difficulty in breathing or swallowing; 4.The swelling of thyroid gland is accompanied by change in voice; 5.The swelling is poorly adherent to the surrounding tissues; 6.The swelling is very hard on palpation; 7.There are thyroid cancer patients in the family; 8.Lymph nodes are palpated on the same side of the swelling. The gold standard of thyroid cancer diagnosis is cytological examination by fine needle aspiration. Besides, the progress of thyroid cancer can be obtained by radionuclide imaging. Thyroid fine needle aspiration is a method of using a general medical syringe to draw out a small amount of cells from the area where thyroid cancer is suspected and examine it with a microscope. Because it is a fine needle syringe, there is little pain and no local anesthesia, and there are almost no side effects. At the same time, the test is inexpensive and the accuracy rate is up to 90%, which is a common test method in the world. Imaging examinations include ultrasound, CT, MRI, PET, etc. Among them, the most basic and preferred examination method is ultrasound. Ultrasonography can observe the morphological characteristics of the nodes and also help to identify whether the enlarged lymph nodes are metastases; CT and MRI, as morphological examinations, can obtain the relationship between the lesions and the surrounding tissues; PET, as a systemic metabolic examination, can understand the extent of the spread of the lesions.