Prognostic evaluation of the proposed residual tumor classification in a Chinese non-small cell lung cancer population.

Abstract

This study aimed to validate the R classification including uncertain resection (R-un) proposed by the International Association for the Study of Lung Cancer (IASLC) in a Chinese non-small cell lung cancer (NSCLC) population. The study retrospectively investigated a 2009-2013 single-institutional NSCLC resection cohort in China. After reclassification, recurrence-free survival (RFS) and overall survival (OS) were calculated using survival analyses and compared with those using the 2005 version IASLC R classification. Under the proposed stratification, 3819 (72.1%) individuals were classified as R0, 1371 (25.9%) as R-un, 71 (1.3%) as R1, and 32 (0.6%) as R2. The 5-year OS probabilities for the R0, R-un, and R1/R2 groups were 71%, 46%, and 34%, respectively. The prognostic stratification remained significant in the fully adjusted Cox models (p < 0.001). Compared with the original classification, Harrell's concordance index of reclassification improved significantly, from 0.508 to 0.679 for RFS and from 0.510 to 0.692 for OS (RFS: p = 0.007; OS: p = 0.001). The survival analysis showed that R-un patients with highest mediastinal lymph node station metastasis had significantly worse survival than R0 patients with mediastinal nodal metastasis (RFS: 44 vs. 36 months, hazard ratio [HR]: 1.29, p < 0.001; OS: 59 vs. 50 months, HR: 1.34, p < 0.001). Cox proportional hazards regression analysis showed that highest mediastinal lymph node station metastasis was an independent risk factor for RFS (HR: 1.22) and OS (HR: 1.25). The proposed R classification showed valid prognostic stratification, including highest mediastinal nodal station metastasis.