The International Association for the Study of Lung Cancer Thymic Epithelial Tumors Staging Project: An Overview of the Central Database Informing Revision of the Forthcoming (Ninth) Edition of the TNM Classification of Malignant Tumors

Introduction: In 2014, a TNM-based system for thymic epithelial tumors was proposed. The TNM stage classification system was published as a result of a joint project from the International Association for the Study of Lung Cancer and the International Thymic Malignancy Interest Group for the eighth edition of the American Joint Commission on Cancer and the Union for International Cancer Control stage classification system. The Thymic Domain of the Staging and Prognostic Factors Committee of the International Association for the Study of Lung Cancer received the mandate to make proposals for the ninth edition of the TNM stage classification. Methods: A central thymic database was collected by the Cancer Research And Biostatistics with the contribution of the major thymic associations in the world. Results: A total of 11,347 patients were collected. Submitting organizations were the following: Japanese Association for Research in the Thymus, European Society of Thoracic Surgeons, Chinese Alliance for Research in Thymoma, Korean Association for Research in the Thymus, International Thymic Malignancy Interest Group, and Réseau tumeurs THYMiques et Cancer. Additional contributions came from centers in the United States, United Kingdom, Turkey, Australia, Spain, and Italy. A total of 9147 cases were eligible for analysis. Eligible cases for analysis came from Asia and Australia (5628 cases, 61.5%), Europe (3113 cases, 34.0%), and North America (406 cases, 4.4%). Conclusions: This report provides an overview of the database that has informed the proposals for the updated T, N, and M components and the stage groups for the ninth TNM of malignant tumors.