Prognostic Significance of the Extent of Lymph Node Involvement in Stage II-N1 Non-small Cell Lung Cancer

Background: The non-small cell lung cancer (NSCLC) staging system (published in 2009 in the seventh edition of the cancer staging manuals of the Union for International Cancer Control and American Joint Commission on Cancer) did not include any changes to current N descriptors for NSCLC. However, the prognostic significance of the extent of lymph node (LN) involvement (including the LN zones involved [hilar/interlobar or peripheral], cancer-involved LN ratios [LNRs], and the number of involved LNs) remains unknown. The aim of this report is to evaluate the extent of LN involvement and other prognostic factors in predicting outcome after definitive surgery among Chinese patients with stage II-N1 NSCLC. Methods: We retrospectively reviewed the clinicopathologic characteristics of 206 patients with stage II (T1a-T2bN1M0) NSCLC who had undergone complete surgical resection at Shanghai Chest Hospital from June 1999 to June 2009. Overall survival (OS) and disease-free survival (DFS) were compared using Kaplan-Meier statistical analysis. Stratified and Cox regression analyses were used to evaluate the relationship between the LN involvement and survival. Results: Peripheral zone LN involvement, cancer-involved LNR, smaller tumor size, and squamous cell carcinoma were shown to be statistically signifi cant indicators of higher OS and DFS by univariate analyses. Visceral pleural involvement was also shown to share a statistically signifi cant relationship with DFS by univariate analyses. Multivariate analyses showed that tumor size and zone of LN involvement were signifi cant predictors of OS. Conclusions: Zone of N1 LN, LN ratios, and tumor size were found to provide independent prognostic information in patients with stage II NSCLC. This information may be used to stratify patients into groups by risk for recurrence.