The best treatment for differentiated thyroid cancer is the “triple” approach of subtotal thyroidectomy + isotope 131 iodine therapy + oral levothyroxine. As with most malignant tumors, surgery is the preferred treatment for thyroid cancer. However, the extent of thyroidectomy for differentiated thyroid cancer has long been the subject of surgical debate due to the high recurrence rate (median 35%) after surgery. The actual practice varies greatly due to different views. The overall treatment options are subtotal thyroidectomy and subtotal thyroidectomy, and there are at least four options for subtotal thyroidectomy: (1) partial excision of one lobe; (2) excision of one lobe and isthmus; (3) partial excision of one lobe + isthmus + contralateral lobe; (4) subtotal excision of one lobe + isthmus + contralateral lobe. In 1988, WHO proposed the definition of thyroid micro-carcinoma (TMC): thyroid carcinoma with a maximum diameter of ≤1 cm, regardless of the presence of regional lymph nodes or distant lymph node metastasis, is called TMC. TMC is more common in well-differentiated papillary carcinoma. In the literature, the incidence of papillary thyroid microfocal carcinoma in autopsy thyroid specimens is about 5.6%, accounting for 4.2% of thyroid surgeries in the same period and 47.9% of differentiated thyroid carcinomas, and 3.0% of those with clinically non-palpable thyroid masses. TMC is difficult to be detected early and preoperative diagnosis is more difficult because of its small diameter, very few spontaneous symptoms and slow clinical progression. There are even metastatic lesions at the cellular level that are inaccessible to the naked eye (studies have found that microscopic detection of metastases in the contralateral gland of differentiated thyroid cancer can reach 38%-87%), so it is also difficult to diagnose intraoperatively. It is speculated that TMC is likely the main reason for the high recurrence rate after conventional surgery for this disease. Since the early diagnosis of TMC and the presence of TMC in the thyroid gland seen intraoperatively with the naked eye are difficult to determine, clinical research has shifted the focus to the exploration of new therapeutic approaches. It has been demonstrated that isotope 131 iodine therapy given after surgical treatment of thyroid cancer is effective in removing residual thyroid tissue and TMC at the cellular level and preventing tumor recurrence. It has been reported in the literature that the recurrence rate of thyroid cancer is about 35% after surgical resection, but it can be reduced to 1%-2.5% if postoperative 131 iodine therapy is combined with higher dose of levothyroid hormone replacement therapy. It has also been reported that the recurrence rate of nail cancer is as high as 32.0% with surgery alone; 11% with surgery + oral thyroid hormone; and only 2.7% with surgery + 131 iodine therapy + oral levothyroxine (eugenol). Foreign data reported that the mortality rate of patients treated with 131 iodine after surgery was 3.8 – 5.2 times lower than that of patients treated with surgery alone, and the recurrence rate was 4 times lower. Currently, many scholars at home and abroad are implementing the “triple” treatment plan for differentiated thyroid cancer. Although the “three-in-one” treatment plan for differentiated thyroid cancer has been increasingly accepted by the industry, different scholars still have different opinions on the extent of resection for different lesions. Most physicians advocate near-total thyroidectomy, removing as much of the thyroid as possible, but only if the parathyroid glands and the laryngeal nerve are protected. In fact, total thyroidectomy is associated with high complications and is extremely unnecessary, as high doses of 131 iodine are effective in removing residual functional thyroid tissue from the neck after surgery. Another consideration in favor of near-total thyroidectomy is that it is more effective to remove postoperative residual thyroid with 131 iodine because the number of residual thyroid glands is small and the dose of 131 iodine required is also small. In addition, near-total excision will cause hypothyroidism and increased TSH, which can be more sensitive to determine early functional metastases. Most of the current clinical surgical treatment for nail cancer is based on the ③④ protocol. The thyroid hormone produced by the thyroid tissue left behind simply cannot meet the metabolic needs of the body and is meaningless from a physiological point of view! But it leaves the hidden danger of possible recurrence! Once recurrence or metastasis occurs, treatment will be even more difficult. Therefore, the best treatment for differentiated thyroid cancer is to give sufficient amount of thyroid hormone suppression therapy after complete removal of thyroid tissue by surgery and 131 iodine!