The IASLC Lung Cancer Staging Project: Proposals for the Revision of the M Descriptors in the Forthcoming 9th edition of the TNM Classification of Lung Cancer

Kwun M Fong; Adam Rosenthal; Dorothy J Giroux; Katherine K Nishimura; Jeremy Erasmus; Yolande Lievens; Mirella Marino; Edith M Marom; Paul Martin Putora; Navneet Singh; Francisco Suárez; Ramon Rami-Porta; Frank Detterbeck; Wilfried Ee Eberhardt; Hisao Asamura; Members of the International Association for the Study of Lung Cancer Staging and Prognostic Factors Committee, Members of the Advisory Boards, and Participating Institutions of the Lung Cancer Domain.

doi:10.1016/j.jtho.2024.01.019

The IASLC Lung Cancer Staging Project: Proposals for the Revision of the M Descriptors in the Forthcoming 9th edition of the TNM Classification of Lung Cancer

J Thorac Oncol. 2024 Feb 4:S1556-0864(24)00060-1. doi: 10.1016/j.jtho.2024.01.019. Online ahead of print.

Authors

Kwun M Fong¹, Adam Rosenthal², Dorothy J Giroux², Katherine K Nishimura², Jeremy Erasmus³, Yolande Lievens⁴, Mirella Marino⁵, Edith M Marom⁶, Paul Martin Putora⁷, Navneet Singh⁸, Francisco Suárez⁹, Ramon Rami-Porta¹⁰, Frank Detterbeck¹¹, Wilfried Ee Eberhardt¹², Hisao Asamura¹³; Members of the International Association for the Study of Lung Cancer Staging and Prognostic Factors Committee, Members of the Advisory Boards, and Participating Institutions of the Lung Cancer Domain.

Affiliations

¹ Department of Thoracic Medicine, The Prince Charles Hospital, University of Queensland Thoracic Research Centre, Brisbane, Australia. Electronic address: kwun.fong@health.qld.gov.au.
² Cancer Research And Biostatistics (CRAB), Seattle, Washington.
³ Department of Thoracic Imaging, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
⁴ Department of Radiation Oncology, Ghent University Hospital and Ghent University, Gent, Belgium.
⁵ Department of Pathology, IRCCS Regina Elena National Cancer Institute, Rome, Italy.
⁶ Department of Diagnostic Imaging, Chaim Sheba Medical Center, Tel-Aviv University, Ramat Gan, Israel.
⁷ Department of Radiation Oncology, Kantonsspital St. Gallen, St. Gallen, Switzerland and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Switzerland.
⁸ Lung Cancer Clinic, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India.
⁹ Department of Thoracic Surgery, Clínica Santa María, Universidad de Los Andes, Santiago, Chile.
¹⁰ Department of Thoracic Surgery, Hospital Universitari Mutua Terrassa, University of Barcelona,Terrassa, Barcelona, Spain; and Network of Centres for Biomedical Research in Respiratory Diseases (CIBERES) Lung Cancer Group, Terrassa, Barcelona, Spain.
¹¹ Department of Surgery, Division of Thoracic Surgery, Yale University School of Medicine, New Haven, CT.
¹² Department of Medical Oncology, West German Cancer Center, University Medicine Essen and Ruhrlandklinik, University Duisburg-Essen.
¹³ Division of Thoracic Surgery, Keio University School of Medicine, Tokyo, Japan.

PMID: 38320664
DOI: 10.1016/j.jtho.2024.01.019

Abstract

Introduction: This study analyzed all metastatic categories of the current tumor, node, and metastasis (TNM) classification of non-small cell lung cancer to propose modifications of the M component in the next edition (9^th) of the classification.

Methods: A database of 124,581 patients diagnosed between 2011 and 2019 was established; of these, 14,937 with NSCLC in stage IVA-IVB were available for this analysis. Overall survival was calculated using the Kaplan-Meier method, and prognosis assessed using multivariable-adjusted Cox proportional hazards regression.

Results: The 8^th edition M categories demonstrated good discrimination in the 9^th edition dataset. Assessments demonstrated that an increasing number of metastatic lesions was associated with decreasing prognosis; because this appears to be a continuum and adjustment for confounders was not possible, no specific lesion number was deemed appropriate for stage classification. Among tumors involving multiple metastases, decreasing prognosis was seen with an increasing number of organ systems involved. Multiple assessments, including after adjustment for potential confounders, demonstrated that patients with M1c patients who had metastases to a single extrathoracic organ system were prognostically distinct from M1c patients who had involvement of multiple extrathoracic organ systems.

Conclusions: These data validate the 8^th edition M1a and M1b categories, that are recommended to be maintained. We propose the M1c category be divided into M1c1 (involvement of a single extrathoracic organ system) and M1c2 (involvement of multiple extrathoracic organ systems).

Keywords: Lung cancer; Metastases; Non–small cell lung cancer; stage IV lung cancer; stage classification.