Thyroid cancer is one of the common malignant tumors of the endocrine system, accounting for about 1% of all malignant tumors in the body, and its incidence has been increasing year by year in China in recent years. Over 90% of thyroid cancers are differentiated thyroid cancers. Most differentiated thyroid cancers progress slowly and can achieve long-term survival through a multidisciplinary and comprehensive diagnosis and treatment strategy. However, there are some tumors that are prone to invasive metastasis and have a relatively poor prognosis. 1. Iodine and thyroid cancer. Iodine is an essential micronutrient for human body, and iodine deficiency can lead to decrease in synthesis and secretion of thyroid hormones and increase in thyroid stimulating hormone (TSH) level, which can lead to hypertrophy of thyroid follicles and even nodules or cancer. A diet high in iodine can also alter the structure and function of the thyroid gland and may increase the incidence of papillary thyroid cancer. The correct approach is to consume iodized salt or iodine-rich foods such as seaweed and nori in moderation to ensure the physiological needs, neither too much nor too little is desirable. 2. Radiation and thyroid cancer. History of childhood exposure to head and neck radiation or radioactive dust, and history of whole body radiation therapy have been identified as risk factors for thyroid cancer. In the past, it was thought that irradiation for head and neck malignancies, such as lymphoma, increased the incidence of thyroid cancer. It is worth mentioning that some studies in recent years have confirmed that the incidence of thyroid cancer in children undergoing dental surface tomography for various dental disorders increases nearly twofold. 3. Family genetic factors and thyroid cancer. Family history of DTC, medullary thyroid carcinoma or multiple endocrine adenomatosis type 2 (MEN2), familial polyposis, etc. are also risk factors for thyroid cancer. In addition, some familial syndromes or hereditary diseases such as Cowden syndrome, Werner syndrome and Gardner syndrome also have a tendency to combine with DTC. 4. Thyroid nodules and thyroid cancer. Most patients with thyroid nodules do not have clinical symptoms. If sudden onset of hoarseness, difficulty in swallowing or breathing occurs, one should be highly alert to the possibility of thyroid cancer invading nerves or rapid growth of tumor compressing surrounding tissues. In addition, if a thyroid nodule becomes hard and immobile, or if a mass (possibly an enlarged lymph node) is palpable in the rest of the neck, the possibility of thyroid cancer should be considered and must be treated as soon as possible. All patients with thyroid nodules should be monitored regularly for TSH levels, and if TSH is found to be elevated then appropriate doses of thyroxine suppressive therapy should be given to reduce the risk of cancer induction. Ultrasound of the neck is a necessary test for all patients with thyroid nodules. 5.Eating habits and lifestyle. Studies have confirmed that metabolic disorders caused by obesity can increase the risk of thyroid cancer. Therefore, improving the diet structure, increasing the intake of fresh vegetables and fruits, and exercising properly to control weight and reduce obesity can also play a positive role in thyroid cancer prevention. In addition, keeping a happy mood, self-regulating tension, releasing mental stress, and strengthening physical exercise also have a positive effect on the prevention of thyroid cancer. Finally, we advocate prevention as the primary prevention for tumors in any part of the body. Above we mainly talk about primary prevention, that is, prevention against the cause of the disease. Secondary prevention refers to early detection and diagnosis. Regular health checkups are very important for early detection of the disease. Specifically for thyroid cancer prevention, we recommend regular ultrasound examination of the neck and measurement of thyroid hormone and TSH levels, especially for those who have risk factors for thyroid cancer.