[Comparison of the Masaoka-Koga Classification with the New TNM Staging of the IASLC/ITMIG for Thymoma and Thymic Carcinoma].

BACKGROUND: The Masaoka-Koga classification describes the extent and spread of thymic epithelial malignancies. The objective of this study was to evaluate the Masaoka-Koga and the new TNM-staging system regarding differences in stage distributions, clinical implementation and therapeutic consequences.

METHODS: Retrospective analysis of all patients who underwent surgery between January 2005 and December 2015 for thymoma/thymic carcinoma in two centres for thoracic surgery. The final tumour stages were determined on the basis of preoperative imaging, surgical reports and histological findings.

RESULTS: A total of 118 patients (male 51%) with a mean age of 56 ± 14.8 years were included. Indications for surgery were primary mediastinal tumour (n = 97), pleura dissemination (n = 15) or mediastinal recurrence (n = 7). Radical tumour resection was performed in 92% of patients (n = 109) within one operation, whereas 8% of patients (n = 9) underwent two operations. Surgical revision was necessary in 12 patients (10.1%) and in-hospital mortality was 1.7% (n = 2). Early Masaoka-Koga stages I (n = 34) and II (n = 16) shifted to the new UICC stage I (T1: n = 58). Locally advanced stages (Masaoka-Koga stage III n = 22 vs. UICC stage IIIA + IIIB n = 20) and metastasised stages (Masaoka-Koga stage IV n = 36 vs. UICC stage IV n = 39) remained very similar.

CONCLUSIONS: The new TNM staging system gave rise to changes, especially in early stages (downstaging), but these had no therapeutic implications. Although advanced stages were very similar, the new TNM staging provides more clinically relevant differentiation.