The IASLC Mesothelioma Staging Project: Proposals for the M Descriptors and for Revision of the TNM Stage Groupings in the Forthcoming (Eighth) Edition of the TNM Classification for Mesothelioma

Journal of Thoracic Oncology 2016 September 27 [Epub ahead of print] [Link]

Rusch VW, Chansky K, Kindler HL, Nowak AK, Pass HI, Rice DC, Shemanski L, Galateau-Sallé F, McCaughan BC, Nakano T, Ruffini E, van Meerbeeck JP, Yoshimura M; Staging and Prognostic Factors Committee, Advisory Boards and Participating Institutions


The metastasis (M) component and TNM stage groupings for malignant pleural mesothelioma (MPM) have been empiric. The International Association for the Study of Lung Cancer developed a multinational database to propose evidence-based revisions for the 8th editions of the tumor, node and metastases (TNM) classification of MPM.
Data from 29 centers were submitted either electronically or by transfer of existing institutional databases. The M component, as it currently stands was validated by confirming sufficient discrimination (by Kaplan Meier) with respect to overall survival (OS) between the clincal (c)M0 and cM1 categories. Candidate stage groups were developed using a recursive partitioning and amalgamation (RPA) algorithm applied to all cM0 cases.
Of 3,519 submitted cases, 2,414 were analyzable and 84 cases were cM1. Median OS for cM1 was 9.7 months versus 13.4 months (p=.0013) for the locally advanced (T4 or N3) cM0 cases, supporting inclusion of only cM1 in the stage IV group. Exploratory analyses suggest a possible difference in OS for single versus multiple site cM1. RPA generated survival tree on the OS outcomes restricted to cM0 with newly proposed (8th edition) T and N components, indicates that optimal stage groupings for the 8th edition will be: stage IA (T1N0), stage IB (T2-3N0), stage II (T1-2N1), stage IIIA (T3N1), stage IIIB (T1-3N2 or any T4), and stage IV (any M1).
This first evidence-based revision of the TNM classification for MPM leads to substantial changes in the T and N components and the stage groupings.