Unification of T2a and T2b Tumors to T2 Tumors in Non-Small Cell Lung Cancer Staging

Abstract

Introduction: We investigated the validation of the seventh edition of the TNM staging (2009) system for lung cancer, retrospectively.
Methods: From January 1990 to March 2004, 1629 patients who underwent lung resection with systemic lymph node dissection for non-small cell lung cancer at Nippon Medical School and Saitama Cancer Center were included. The overall survivals after surgery by each pathological stage according to the 1997 and 2009 systems were statistically analyzed using Kaplan-Meier estimated survival curves, and the significance of the difference was analyzed by the log-rank test.
Results: The 2009 system had significant prognostic distinction between each T descriptor except for T2a and T2b, and between each M descriptor. The 2009 system had better prognostic distinction between each pathological stage except for stages IB and IIA, and stages IIIB and IV. In the simulation, we unified T2a and T2b tumors into T2 tumors, and T2bN0M0 and T2bN1M0 were moved to stages IB and IIA, respectively. This proposed system had significant prognostic distinction between the proposed IB, IIA, and IIB stages.
Conclusions: The 2009 system provides better patient selection for surgery and prognostic distinction between each stage except for stages IB and IIA, and stages IIIB and IV, compared with the 1997 system. Unification of T2a and T2b tumors to T2 tumors can improve prognostic distinction between stages IB and IIA.