Japanese general rules for the description of thyroid cancer (9th edition) established by the Japan Association of Endocrine Surgery and the Japanese Society of Thyroid Pathology

The Japan Association of Endocrine Surgery and the Japanese Society of Thyroid Pathology developed the Japanese General Rules for the Description of Thyroid Cancer (JRTC) in accordance with actual medical practice in Japan to describe clinical findings and unify the pathological diagnosis of thyroid tumors. The 9th Japanese edition of the JRTC was published in 2023 based on the revision of the TNM classification (AJCC) and the WHO tumor classification. In the clinical portion, subclassification of N factor according to the size and extranodal extension of metastatic nodes, subclassification of surgical Ex according to the organs to which carcinoma invades, and the abolishment of preoperative and pathological Ex were major changes from the last edition. In the pathological portion, the tumor classification was rearranged according to the differentiation and malignancy based on the genetic alterations. Adenomatous goiter was classified as a tumor-like lesion. Low-risk neoplasms were placed between benign and malignant tumors, scoring the nuclear findings of papillary carcinoma, and clearly indicating the findings for capsular and vascular invasion of follicular tumors. High-grade differentiated carcinoma was added as a reference to poorly differentiated carcinoma. Oncocytic adenoma and carcinoma were classified independently. The cytology reporting system was partly modified from the Bethesda 2023 system. This translated edition facilitates the submission of Japanese clinicopathological studies of thyroid tumors to international journals and is expected to contribute to the improvement and standardization of the description of the surgical treatment and pathological diagnosis of thyroid tumors. (242 words)