Lymph Node Assessment and Impact on Survival in Video-Assisted Thoracoscopic Lobectomy or Segmentectomy

Background The objective of this study was to evaluate the influence of total number of resected lymph nodes, lymph node ratio, and the number of lymph node stations sampled on prognosis in patients with early stage non-small cell lung cancer (NSCLC) treated with video-assisted thoracoscopic surgery (VATS). Methods Five hundred and fifty patients who underwent VATS lobectomy or segmentectomy for early clinical stage NSCLC were retrospectively analyzed from 2006 to 2012. Disease-free survival (DFS) and overall survival (OS) were compared for cutoff values of total number of resected lymph nodes (RNs) and lymph node stations (LNS) using Kaplan-Meier methods and Cox proportional hazard models. Results Lobectomy was performed in 493 (90%) patients with a median follow-up of 2.7 years. Median age was 68 (range, 29 to 92 years) and 342 (62%) were female. Pathologic stage I, II, and III was observed in 434 (79%), 80 (14.5%) and 36 (6.5%) patients, respectively. The N0, N1, and N2 pathologic nodal status was observed in 485 (88%), 38 (7%), and 27 (5%) patients, respectively. Nodal upstaging was observed in 11.3% (59 of 550) in the total cohort and 15% (49 of 332) in patients who underwent LNS greater than 3 compared with 5% (10 of 218) in patients with LNS 3 or less ( p < 0.01). Multivariate analysis identified LNS greater than 3 as a negative independent predictor for DFS (hazard ratio 2.36, p = 0.003) and OS (hazard ratio 1.77, p = 0.046). Conclusions Sampling greater than 3 LNS and greater than 10 RNs was associated with an increase in nodal upstaging. Only LNS greater than 3 was found to be an independent predictor of mortality in VATS lobectomy and segmentectomy in clinical early-stage NSCLC.