Validation of the Eighth Edition of the TNM Staging System for Lung Cancer in 2043 Surgically Treated Patients With Non–small-cell Lung Cancer

Abstract

PurposeThe International Association for the Study of Lung Cancer has proposed a revision of the Tumor, Node, Metastasis (TNM) classification for lung cancer. The purpose of this study is to evaluate the prognostic value of the eighth edition of the TNM staging system in surgically treated patients with non–small-cell lung cancer. MethodsData from 2043 consecutive patients with non–small-cell lung cancer who underwent surgical treatment in our single center between January 2006 and September 2015 were collected and analyzed retrospectively. Cox proportional hazard models were used to assess the prognostic significance of the T and N descriptors. ResultsThe reversed overall survival curves of stage IIA and stage IIB in the seventh edition were corrected in the eighth edition. Better prognostic value in predicting overall survival, including a higher log rank test of trend χ2 statistic (433.6 vs. 414.2), a smaller Akaike Information Criterion value (4759.6 vs. 4768.2), a higher Harrell C-index (0.776 vs. 0.769), and a lower integrated Brier score (0.092 vs. 0.093), was observed for the eighth edition relative to the seventh edition. Recurrence-free survival analysis of subsets of patients stratified by T and N descriptors showed a stepwise deterioration. Significant differences were found between patients of subdivided stage IA (IAI vs. IA2; P = .003 and IA2 vs. IA3; P = .004). ConclusionThe eighth edition of the TNM staging system for lung cancer has prognostic value superior to that of the seventh edition. It was able to predict recurrence-free survival well.