Staging of thymic epithelial tumours — state of the art

The year 2025 marks a pivotal moment in the staging and management of thymic epithelial tumours, with the recommended implementation of the 9th edition of the TNM classification, published in 2023 through a collaborative effort between the International Thymic Malignancies Interest Group (ITMIG) and the Thymic Domain of the Staging and Prognostic Factors Committee (TD-SPFC) of the International Association for the Study of Lung Cancer (IASLC). This paper provides a comprehensive overview of the current state of thymic tumour staging, focusing on the historical Masaoka-Koga classification, the histological WHO classification, and the more recent TNM (Tumor–Nodes– Metastasis) system, with particular attention to the updates introduced in the 9th TNM edition. We also discuss the limitations of existing staging systems and highlight emerging trends in the field. Finally, the paper explores strategies for prognostic assessment in patients with thymic tumours, emphasizing recent refinements in staging and prognostic evaluation.