Early thyroid cancer generally does not need to take iodine-131, and middle and late thyroid cancer will take iodine-131 treatment about one month after surgery. 1. Early thyroid cancer: If early thyroid cancer patients can be detected, diagnosed and treated at an early stage, most of the early thyroid cancer patients can be clinically cured through radical surgical resection, and generally do not need Iodine-131 radiotherapy after surgery. 2. Intermediate and advanced thyroid cancer: patients with intermediate and advanced thyroid cancer have a higher risk of recurrence after surgery, and usually need to use iodine-131 treatment one month after surgery to control their condition and prevent recurrence. Besides, iodine-131 is usually needed to refer to differentiated thyroid, i.e. papillary thyroid cancer and follicular thyroid cancer. These two pathological types of thyroid cancer have relatively strong iodine uptake ability, and postoperative Iodine-131 treatment is conducive to consolidating the therapeutic effect; for medullary thyroid cancer and undifferentiated thyroid cancer, Iodine-131 treatment is not done.