Le TNM : la 9e édition pour l'oncologie thoracique

Abstract

The 9^th TNM edition for lung cancer is based on a database of 124,581 cases, of which 18.9% were entered prospectively. Regarding the T component no changes are implemented as the 8^th edition descriptors performed well in the new database. Concerning the N component, N2 is subdivided into N2a and N2b representing single station and multiple stations N2 involvement, respectively. Individual lymph nodes in each station are not counted. With regard to the M component, M1c is subdivided into M1c1 and M1c2 when multiple extrathoracic metastases are present in a single organ system or multiple organ systems, respectively. Bone and muscle are counted as a single organ system. Especially the new N descriptors have an impact on the overall stage groupings, whereby e.g. T1N1 belongs to stage IIA and T1N2a to stage IIB. M1c1 and M1c2 both belong to stage IVB.

For staging of thymic epithelial tumours comprising thymoma and thymic carcinoma, the 9^th edition is based on analysis of 9,147 cases. Changes are only proposed in the T component: T1a characterizes tumors until 5 cm and T1b tumors larger than 5 cm in greatest dimension. T2 denotes partial or full-thickness pericardial invasion but also direct invasion into lung parenchyma or phrenic nerve. Invasion of mediastinal pleura is now separately considered as additional histologic descriptor. There are no changes in the stage groupings with both T1a and T1b belonging to stage I.

Regarding pleural mesothelioma, after analysis of a database of 3,481 cases, important changes are proposed for the clinical T descriptors and no changes are implemented for the N and M descriptors. Maximal pleural thickness is now measured at 3 levels on axial CT slices: at upper, middle and lower chest and a sum of the 3 measurements is made (Psum). On a sagittal image maximal pleural thickness in the fissure is measured as Fmax. Cut-off values for Psum are 12 and 30 mm, and for Fmax 5 mm. These will finally determine the specific T-category. For a pathologist it is not possible to perform exactly the same measurements on a resected specimen and for this reason, only the clinical stage groupings were redefined without any changes in the pathological stage groupings. 1877-1203/© 2025 SPLF. Published by Elsevier Masson SAS. All rights reserved.