The prognostic value of ratio-based lymph node staging in resected non-small-cell lung cancer.

INTRODUCTION: Assessment of lymph node status is a critical issue in the surgical management of non-small-cell lung cancer (NSCLC). We sought to determine the prognostic value of metastatic lymph node ratio (LNR) in patients with radical surgery for NSCLC.

METHODS: We abstracted data from 480 consecutive patients undergoing radical surgery for NSCLC between 2006 and 2008 in our institution. Kaplan-Meier estimated the survival function using the number of metastatic lymph node (MLN) and LNR as categorized variables. The prognostic value of age, sex, smoking status, location of tumor, histology, pathology T stage, pathology N stage, surgical procedure, chemotherapy, MLN, and LNR were assessed using a multivariate Cox proportional hazards model for overall survival (OS) and disease-free survival (DFS).

RESULTS: The median numbers of examined lymph nodes and MLNs were 15 and 5, respectively. Optimal cutpoints of the LNR were calculated as 0, 0 to 0.35, and greater than 0.35. Patients with higher LNR were associated with worse OS and DFS in the whole series, whereas there was no significant difference in the OS and DFS of those patients classified as pathology N2. A multivariate analysis showed that the LNR staging, smoking status, and chemotherapy were revealed to be independent prognostic factors.

CONCLUSIONS: LNR is an independent predictor of survival in patients with NSCLC undergoing radical resection; the prognostic significance is more valuable in patients classified as pathology N1.