Regarding the causes of thyroid cancer, they are similar to most malignant tumors. The etiology of thyroid cancer is currently unclear, but some factors have been found to be associated with the onset of thyroid cancer. The first factor is neck radiation; the thyroid is an endocrine organ that is sensitive to radiation, so radiation exposure may cause carcinogenic changes in thyroid cancer cells. The second factor is genetics; some thyroid cancers have a clear genetic predisposition, the most typical being medullary thyroid cancer, with about 25% of patients showing familial clustering, known as familial medullary thyroid cancer. The third factor is that the rapid increase in the incidence of thyroid cancer also has some reasons, with one recognized reason being advancements in early diagnostic methods, allowing for the easy detection of numerous early lesions. The fourth is iodine intake, which has been shown to be related to some benign diseases of the thyroid, but its relationship with thyroid cancer itself needs further study.