Comparison of 6th, 7th, and 8th editions of the TNM staging in non-small cell lung cancer patients: Validation of the 8th edition of TNM staging

Abstract

Background: In this study, we aimed to evaluate the effects of the transition from the 6th edition of the Tumor, Node, Metastasis (TNM) staging system to the 7th edition, and from the 7th edition to the 8th edition by comparing the stage migrations. We also aimed to externally validate the 8th edition of the TNM staging system. Methods: Between September 2005 and June 2015, a total of 1,077 patients (986 males, 91 females; mean age: 59.6±8.3 years; range, 35 to 84 years) with non-small cell lung cancer who underwent lung resection were retrospectively analyzed. We re-staged patients according to 6th, 7th, and 8th TNM staging and compared the stage migrations of cases among the three staging systems. Results: Stage migration in the transition to the 7th edition of the TNM staging system was observed in 368 (34.1%) patients whereas it was observed in 541 (50.2%) patients in the transition to the 8th edition (p<0.001). The rate of upstaging in transition to the 7th edition staging system was 50.2% (n=185), whereas it was 98.1% (n=531) for the transition to the 8th edition (p<0.001). The survival rates of Stages 1B, 2B and 3A increased with transition to the 7th edition and the survival rates of Stages 1B, 2A, 2B, 3A, and 3B increased with the transition to the 8th edition. The best stratification in the survival curves in the 6th edition was between 1B-1A and 3B-3A. In the 7th edition, it occurred between 1B-1A, 3A-2B and 3B-3A and, in the 8th edition, between 1B-1A and 3B-3A. Conclusion: Stratification according to the 7th edition showed better prognostic validity compared to the 6th edition; and that of the 8th edition was better compared to the 7th edition.