Impact of the 8th Edition of the UICC-TNM Classification on Clinical Stage 0-IA Lung Adenocarcinoma: Does the New Classification Predict Postoperative Prognosis More Precisely than the Previous One?

Purpose: Early lung adenocarcinoma has been more frequently found recently. The 8th edition of the Union for International Cancer Control (UICC)-Tumor Node Metastasis (TNM) classification for lung cancer has been effective since January 2017. This study aims to elucidate advantages of the current classification for patients with clinical stage 0-IA lung adenocarcinoma, in comparison with the older one. Methods: We retrospectively reviewed the data of clinical stage IA (7th edition) lung adenocarcinoma patients who underwent surgery at our institute from 2001 to 2012, and reclassified them by the 8th edition. Survival analysis was used to evaluate the impact of the two classifications. Results: In all, 281 cases were eligible. Clinical T-factors (8th) were significant prognostic factors for overall survival (P = 0.001), recurrence-free survival (P <0.001), and cancer- specific survival (P = 0.001). However, those in the previous edition were not (P = 0.894, P = 0.144, and P = 0.822, respectively). Conclusion: The 8th edition of the UICC-TNM classification predicts postoperative prognosis more precisely than the 7th one in clinical stage 0-IA lung adenocarcinoma. It is probably because the stage distribution of the population, which included in the research project the 8th edition based on, has been changed, and the new edition develops more accurate staging criteria for ground-glass nodule (GGN).