MA09.05 A Comparison of the Number of Involved Nodal Stations With Currently Used Pathological N Stage on Predicting Prognosis in NSCLC

Abstract

The International Association for the Study of Lung Cancer (IASLC) proposed a new N descriptor by combining anatomical location and number of involved nodal stations (nS). We aimed to validate the prognostic performance of the proposed N descriptor, and further investigate the discriminative ability of nS classification compared with currently used pathological N (pN) stage in a large independent non-small-cell lung cancer (NSCLC) cohort. 4011 NSCLC patients undergoing major pulmonary resection were identified between 2009 and 2013. The optimal cutoff points for nS classification were determined using the X-Tile software. Kaplan–Meier and Cox models were used to analyze the prognostic performance of the proposed N descriptor and nS classification. Decision curve analysis (DCA) was performed to evaluate the standardized net benefit of nS classification in predicting prognosis. The IASLC proposed N descriptor stratified patients into six groups, whereas the differences were not always significant between each pair of comparison in disease-free survival (DFS) and overall survival (OS) (Figure 1). The nS classification we proposed dividing patients into four prognostically different groups (nS0, nS1, nS2, nS ≥ 3), and the prognosis between each group was statistically different (Figure 2). Multivariate Cox analysis demonstrated that nS was an independent prognostic factor in DFS and OS. Furthermore, patients belonging to N1 or N2 stage could be divided into three prognostically different subgroups by nS classification. However, the prognosis was similar between N1 and N2 subgroups when patients staging in the same nS category. The DCA showed that the nS classification tended to have a higher predictive capability than location-based N classification.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The nS classification is a more accurate prognostic determinant than the currently used pN classification in patients with resected NSCLC. The forthcoming 9th TNM classification is worth considering reclassification of the N category by number of involved nodal stations.