One of the rarer and more malignant subtypes of thyroid cancer is medullary carcinoma. More than 50% of this subtype is caused by mutations in the RET gene, and approximately 15% of these are hereditary. Medullary thyroid cancer with RET mutations has a high likelihood of recurrence with conventional treatments, so targeted drugs that target RET mutations have been emphasized. Unfortunately, the RET inhibitors available in the market today are not clinically effective due to their side effects, and there is an urgent need for a better generation of RET inhibitors with fewer side effects. The relationship between iodine intake and thyroid cancer is still not very clear, but some studies have demonstrated that iodine deficiency increases the risk of thyroid cancer, and the main evidence is that the incidence of thyroid cancer is higher in the more iodine-deficient parts of the world, such as Central Asia and Central Africa, than in places by the sea. In addition, patients with goiter due to iodine deficiency have a higher probability of getting thyroid cancer later in life. There is no evidence that excessive iodine supplementation increases the probability of developing thyroid cancer. Some people say that the fact that both iodized and non-iodized salt are sold in the market indicates that the state has realized that too much iodine supplementation is bad. This conspiracy theory has no scientific basis. The main reasons why salt without iodine is available on the market are: iodized salt costs more and there is no need to add iodine in many places where salt is used (e.g. making kimchi); some people have to eat low iodized food (e.g. thyroid cancer patients before preparing for I131 treatment); some people are allergic to iodine, etc.