Why should all thyroid glands be removed for thyroid cancer? The reasons are as follows: 1. For most thyroid cancers, surgery + iodine-131 therapy + thyroid hormone therapy is the best comprehensive treatment plan for thyroid cancer, and in order to facilitate post-operative iodine-131 therapy, improve the efficacy and reduce recurrence, the thyroid gland should be completely removed during surgery as much as possible. 2. Thyroid cancer is generally multifocal in nature, and if the thyroid gland is not completely removed, there are often tiny cancerous tissues remaining in the thyroid tissue after surgery, which will easily grow back into a lump after surgery, resulting in another surgery or even multiple surgeries for the patient. 3. Even for experienced surgeons, re-operation or multiple operations on the thyroid gland often cannot be done perfectly, because the risk of surgery increases greatly, and the possibility of laryngeal nerve injury and parathyroid gland injury increases significantly, which greatly increases the difficulty of surgical operations. 4. Repeat or multiple thyroid surgeries can cause great psychological and physical trauma to the patient and increase the economic burden. Therefore, it is very important to reduce the number of thyroid surgeries. If you can solve the problem completely in one operation, try not to choose another or multiple operations to complete. 5. Some surgeons advocate preserving part of the thyroid tissue in order to retain some of the thyroid function, which is actually of little value. After partial or partial removal of the thyroid gland, patients need exogenous thyroid hormone supplementation (e.g., oral euthyroxine) to achieve thyroid function, which cannot be compensated by the residual thyroid tissue alone. The residual thyroid gland will only be the root cause of thyroid tumor recurrence. The clinical term “total thyroidectomy” is actually “near total thyroidectomy”, because in order to protect the parathyroid tissue, the thyroid gland cannot be completely removed, but only “near total removal”. “This is why the thyroid gland is completely removed. This is the reason why further treatment with iodine-131 is needed after total thyroidectomy. 7. Currently, even for benign multiple thyroid nodules, total thyroidectomy is advocated to reduce postoperative nodal recurrence, thus reducing the risk of re- and multiple thyroid surgeries for patients. 8. Only for a small number of solitary microscopic thyroid tumors with good pathological differentiation and no envelope infiltration or lymphatic metastasis, thyroidectomy or partial thyroidectomy is advocated.