Iodine 131 treatment generally has no effect on lung cancer, and cannot treat primary lung cancer, but only has certain therapeutic effect on thyroid cancer with lung metastasis. Iodine 131 treatment destroys the epithelium of thyroid follicles, causing gradual necrosis of thyroid glands, which in turn reduces the secretion function of the thyroid gland and treats hyperthyroidism, and can also be used to treat thyroid cancer. Moreover, Iodine 131 treatment does not affect neighboring tissues, so it generally does not affect lung cancer. Since Iodine 131 treatment can play a role in treating thyroid cancer, it has a certain therapeutic effect on thyroid cancer with lung metastasis. Lung cancer patients who need Iodine 131 treatment should actively cooperate with doctors in the treatment process in order to get a better prognosis.