Lymph Node Ratio Predicts Recurrence and Survival After R0 Resection for Non-Small Cell Lung Cancer

Background. Current TNM non-small cell lung cancer (NSCLC) staging uses only the anatomic location of lymph nodes to define N status. Several other cancer staging systems have found lymph node ratio (LNR)-the number of positive lymph nodes/total lymph nodes resected-to be a better predictor of survival after resection. The purpose of this study is to evaluate LNR as a predictor of recurrence and survival after R0 resection for NSCLC. Methods. A total of 1,143 consecutive patients underwent R0 resection for NSCLC between 1999 and 2008 at a high-volume single institution with 26% (n = 302) having N1 and N2 disease. The primary endpoints of the study were long-term survival and recurrence as a function of LNR. Cox proportional hazard models and Kaplan-Meier survival analyses were utilized to assess associations between LNR, N status, and pathologic stage with survival and recurrence after lung cancer resection. Results. Median follow-up was 44 months and was complete in 97% of patients. Nodal status of patients in this study was as follows: N0 disease, 73.5%; N1 disease, 18.7%; and N2 disease, 7.8%. There were 132 recurrences in patients with nodal disease (43.7%). The pathologic stage of patients in the study was as follows: stage IIA, 47%; stage IIB, 17%; stage IIIA, 35%; and stage IIIB, 1%. Mean total number of lymph nodes sampled was 11.1 +/- 6.0 and mean number of positive lymph nodes 2.4 +/- 2.0. Upon statistical modeling, LNR was found to be independently associated with decreased survival after resection for NSCLC (hazard ratio 2.63, confidence interval: 1.41 to 4.91, p = 0.002). Conclusions. In patients undergoing resection for NSCLC, increasing lymph node ratio is independently associated with decreased survival and decreased time to recurrence after R0 resection. (C) 2013 by The Society of Thoracic Surgeons