Many thyroid cancers are treated with a “triple” package: thyroid surgery + oral thyroid hormone + 131I radiation therapy. Surgery is the mainstay of thyroid cancer treatment, with chemotherapy and general radiotherapy rarely used. Almost all patients will undergo various degrees of thyroidectomy, including lobectomy, subtotal thyroidectomy or total thyroidectomy, and lymph node dissection if there are lymph node metastases. Many thyroid cancers can be cured if the surgery is done well, so a good experienced surgeon is crucial. Oral thyroid hormone is given to compensate for the lack of your own hormones after thyroidectomy, so there is little doubt. What is more controversial is the radioactive 131I treatment. When people hear that radioactive substances will be injected into the body, they think it is very scary. What exactly is 131I? Is this treatment necessary? 131I is a strong radioactive element that kills cells in high concentrations. 99% of the iodine in the body is absorbed by the thyroid cells, and most thyroid cancer cells retain this property. Therefore, after the thyroid gland has been surgically removed, most of the 131I taken orally or injected will be enriched in the thyroid cancer cells, killing them directly. 131I treatment is actually a very specific micro-radiotherapy with few side effects because other cells in the body do not absorb iodine. Not all thyroid cancer patients need to use 131I . If, for various reasons, surgery cannot completely remove the thyroid cancer cells, or if the cancer cells have metastasized and cannot be removed surgically, then 131I treatment has a very good effect and can significantly reduce recurrence.