This gives these latent cancer cells a chance to “muddle through” and makes it very difficult to detect these “enemy agents” in time. However, we can still look for some “traces” to confirm their existence and nip them in the bud. Generally speaking, the first symptom of thyroid cancer in most patients is a painless mass in the neck, most of which moves up and down with swallowing, and some patients have difficulty swallowing and feel pressure in the neck. Other patients may first find enlarged metastatic lymph nodes in the neck and then the primary lesion in the thyroid gland. Therefore, if you find a mass in your neck that moves with swallowing, or a fixed neck mass larger than 2 cm, you need to seek prompt medical attention. It is also recommended that people over 20 years old, especially white-collar women with excessive mental stress, those with family history of thyroid cancer, those who are often exposed to high radiation work environment, those who are fond of seafood and those who live in coastal areas and other people at high risk of thyroid cancer, should preferably go to a regular hospital for an ultrasound of the thyroid gland once a year. This is a very practical and useful method, and the cost is not too high, at more than $100. Surgery is only the beginning of treatment. There are 3 main treatments for thyroid cancer: the first is surgery, the second is radiotherapy, and the third is oral thyroxine. Surgery is enough for early stage thyroid cancer patients. After surgery, lifelong thyroid hormone replacement therapy under the guidance of doctors is aimed at firstly, making up for the lack of thyroxine in the body, and secondly, it has a certain inhibitory effect on the development of thyroid cancer with few toxic side effects. However, in the process of taking thyroxine tablets, it is necessary to take sufficient amount orally and adjust the dosage according to the examination results: taking too much will cause symptoms of hyperthyroidism, while taking too little will have no effect. After thyroid cancer surgery, in addition to long-term oral thyroxine tablets, you need to receive internal radiation therapy in nuclear medicine department if you have the following 3 conditions: 1. distant metastasis or peripheral invasion visible to the naked eye, regardless of tumor size; 2. primary tumor > 4 cm; 3. 1-4 cm tumor with lymph node metastasis, or other high-risk factors. Commonly, 131 iodine therapy is used because all residual thyroid tissue, and more than 80% of metastases of differentiated thyroid cancer, have the ability to take up radioactive 131 iodine, and when high doses of 131 iodine are administered orally, it will be directed to the lesion site like a biological missile, using the beta rays it releases to completely remove or destroy the residual thyroid tissue or metastases. 131 iodine therapy 131 iodine therapy is necessary for all postoperative patients with differentiated thyroid cancer as it will prevent recurrence and metastasis in patients without metastasis after surgery and effectively treat metastases in patients with existing metastases. 131 iodine therapy is simple and requires only one oral dose. Since it is a biological missile type of treatment, it has less impact on other organs and tissues throughout the body, so there are fewer side effects and complications. Most of the recurrence of thyroid cancer after surgery is within 5 years, and the recurrence site is mostly in the original tumor or neck. Therefore, patients with thyroid cancer should pay special attention to whether there is a palpable mass in the original surgical site or neck. Most of the patients have no conscious symptoms at the early stage of recurrence. Once symptoms such as hoarseness, choking, breath-holding, dysphagia, coughing up blood or joint pain appear, it often indicates that the recurrent cancer has developed to a certain extent. Therefore, postoperative patients should go to the hospital for regular checkups, usually once every 3 months or 6 months in the first 2 years, and once every 6 months or 1 year thereafter. It should be especially noted that it is best to ask the surgeon who performed the original surgery to examine the patient, because they know the patient’s pre- and post-operative conditions. If the previous surgery was not performed in a specialist hospital, it is best to bring the records of the condition to the specialist hospital for examination. Once recurrence is found, it is important not to be pessimistic and give up treatment. At present, the treatment of recurrent cancer is still based on surgical treatment. Most of recurrent thyroid cancers can be completely removed, and even if they cannot be completely removed, patients with a small amount of tumor remaining can still obtain a long survival period.