The IASLC Pleural Mesothelioma Staging Project: Expanded Database to Inform Revisions in the Ninth Edition of the TNM Classification of Pleural Mesothelioma

The International Association for the Study of Lung Cancer (IASLC) collaborated with the International Mesothelioma Interest Group to propose the first tumor, node, and metastasis (TNM) stage classification system for diffuse pleural mesothelioma in 1995, accepted by the Union for International Cancer Control and the American Joint Committee on Cancer for the 6th and 7th edition stage classification manuals. The IASLC Staging and Prognostic Factors Committee Mesothelioma Domain developed and analyzed an international registry of patients with pleural mesothelioma and updated TNM descriptors for the 8th edition of the stage classification system. To inform revisions for the forthcoming 9th edition of the TNM stage classification system, data submission was solicited for patients diagnosed between 2013 and 2022 with expanded data elements based on the first project’s exploratory analyses, including pleural thickness measurements, updated surgical nomenclature, and molecular markers. The resulting database consisted of a total of 3,598 analyzable cases from Europe, Australia, Asia, North America, and South America, with a median age of 71 years (range 18-99), 2,775 (77.1%) of whom were men. With only 1,310 (36.4%) patients undergoing curative intent operations, this iteration of the database includes far more patients treated non-surgically compared to prior. Four separate manuscripts on T, N, M, and stage groupings submitted to this journal will summarize analyses of these data and will serve collectively as the primary source of the proposed changes to the upcoming 9th edition of the pleural mesothelioma stage classification system.