The 8th edition of the TNM classification of lung cancers has been in effect since 2017. These recommendations have been summarized in publications issued by the Union for International Cancer Control (UICC), the American Joint Committee on Cancer (AJCC), and the International Association for the Study of Lung Cancer (IASLC) [1-3]. In January 2024, they will be replaced by the 9th edition of the TNM classification. The Staging and Prognostic Factors Committee of the IASLC and the non-profit organization Cancer Research and Biostatistics (CRAB®) have collaborated in the third staging project to revise the staging system for lung, mesothelioma and thymic cancers based on the data of 87,339 patients. Among these, 83 % and 7 % had NSCLC and SCLC, respectively. Fifty-six percent were Asians or Australians, while 25 % were from Europe and 16 % from North America. At WCLC 2023, Asamura et al. presented the final proposals for the new TNM classification .
Regarding T descriptors, the 9th edition will not recommend any changes compared to the current criteria. Within the N category, the N2 stage has been subdivided: while N2a denotes single N2 station involvement, N2b relates to multiple N2 station involvement. Similarly, the M1c stage will be divided into two subcategories. In patients with multiple extra-thoracic metastases, M1c1 will be used when these lesions are found in a single organ system. If they are located in multiple organ systems, the disease should be classified as M1c2. M1a and M1b, meanwhile, remain as previously defined. Naturally, the changes with respect to N and M descriptors have resulted in a revised TNM stage grouping (Table). For both clinical and pathological stages according to the new definitions, the survival curves showed no significant overlap.
- Union for International Cancer Control. Briely JD, Gospodarowicz MK, Wittekind CH eds. TNM Classification of Malignant Tumors, 8th ed. Oxford UK and Hoboken, NJ: John Wiley; 2017
- American Joint Committee on Cancer. Amin MB ed. AJCC Cancer Staging Manual, 8th ed. Springer; 2017
- International Association for the Study of Lung Cancer. Rami-Porta R, ed. Staging Manual in Thoracic Oncology, 2nd Ed. North Fort Myers: Editorial Rx Press; 2016
- Asamura H, Nishimura K, IASLC 9th edition TNM stage proposal. WCLC 2023, abstract PL04.03
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