Therapeutic Strategy for Differentiated Thyroid Carcinoma in Japan Based on a Newly Established Guideline Managed by Japanese Society of Thyroid Surgeons and Japanese Association of Endocrine Surgeons

BACKGROUND: Therapeutic strategy for patients with differentiated thyroid carcinoma (DTC) in Japan has differed from that in Western countries. Total thyroidectomy followed by radioactive iodine (RAI) ablation has been a standard therapy in Western countries, while limited thyroidectomy has been widely accepted in Japan. We newly established guidelines for clinical practice in treating thyroid tumors based on evidence from previous publications and the accumulation of data from patients in Japan. We present our therapeutic recommendations for DTC patients based on these guidelines. METHODS: From the 55 clinical questions (CQ) in our guideline, we selected CQ regarding the treatment of DTC. We commented on each and compared it with the corresponding regions in Western guidelines. RESULTS: For papillary carcinoma, we strongly or moderately recommend total thyroidectomy for patients with tumors larger than 4 cm, clinical node metastasis, distant metastasis, or significant extrathyroid extension, while hemithyroidectomy is acceptable for T1N0M0 patients. In contrast to Western guidelines, routine central compartment dissection is recommended for papillary carcinoma in our guidelines. Completion total thyroidectomy is recommended for patients who were scheduled for hemithyroidectomy under a preoperative diagnosis of follicular neoplasm and were pathologically confirmed as having follicular carcinoma if the pathological diagnosis indicated widely invasive carcinoma or carcinoma having poorly differentiated components. RAI ablation is also recommended for DTC with aggressive clinicopathological features, but its indication is narrower than that in Western guidelines, not only because of the limitations on RAI, but also because it is our policy that patients without high-risk features do not require RAI ablation. CONCLUSION: It is important to treat DTC patients individually according to their clinicopathological features rather than uniformly. We hope that policies regarding the treatment of DTC patients in Western countries and Japan will find the optimal compromise in the future, leading to the best treatments for patients with thyroid carcinoma all over the world.