The following is a summary of “International Association for the Study of Lung Cancer Thymic Epithelial Tumor Staging Project: Proposal for the T Component for the Forthcoming (Ninth) Edition of the TNM Classification of Malignant Tumors,” published in the November 2023  issue of Pulmonology by Okumura, et al.

The eighth edition of malignant tumor stage classification uses TNM-based thymic epithelial tumor stage classification. The Thymic Domain of the Staging and Prognostics Factor Committee of the International Association for the Study of Lung Cancer created a database to propose the ninth edition stage classification system. For a study, researchers proposed T category definitions for the ninth edition TNM stage categorization of thymic cancers. A global database of 11,347 thymic epithelial tumor patients was created. 

Analysis was done on 9,147 individuals with survival data. Outcome measures were overall survival, freedom-from-recurrence, and cumulative incidence. Separate analysis was done for thymomas, carcinomas, and neuroendocrine tumors. The following are T category proposals: T1 is divided into T1a (≤5 cm) and T1b (>5 cm), regardless of mediastinal pleura invasion. T2 involves direct invasion of the pericardium, lung, or phrenic nerve. 

T3 involves direct invasion of the brachiocephalic vein, superior vena cava, chest wall, or extra pericardial pulmonary arteries and veins. T4 remains unchanged from the eighth edition, involving direct invasion of the aorta and arch vessels, intrapericardial pulmonary artery. The ninth edition TNM classification’s T categories show strong outcome discrimination for the T component of the TNM-based stage system of thymic epithelial cancers.

Source: sciencedirect.com/science/article/abs/pii/S1556086423007517