Rationale for a Minimum Number of Lymph Nodes Removed with Non-Small Cell Lung Cancer Resection: Correlating the Number of Nodes Removed with Survival in 98,970 Patients

Background. The benefit of thoracic lymphadenectomy in the treatment of resectable non-small cell lung cancer (NSCLC) continues to be debated. We hypothesized that the number of lymph nodes (LNs) removed for patients with pathologic node-negative NSCLC would correlate with survival. Methods. The National Cancer Data Base (NCDB) was queried for resected, node-negative, NSCLC patients treated between 2004 and 2014. Patients were grouped according to the number of LNs removed (1-4, 5-8, 9-12, 13-16, and >= 17). Patients with <10 LNs removed were also compared with those with >= 10 LNs removed. A Cox regression analysis was performed and hazard ratios (HRs) calculated, with 95 % confidence intervals (CIs). Results. Of 1,089,880 patients with NSCLC reported to the NCDB during the study period, 98,970 (9.0 %) underwent resection without evidence of pathologic nodal involvement. Lobectomy was performed in 83.9 %, sublobar resection was performed in 12.7 % and pneumonectomy was performed in 2.8 % of patients. The number of LNs removed correlated with increasing tumor size and extent of resection. On multivariate analysis, increasing age, male sex, white ethnicity, high tumor grade, larger tumor size, pneumonectomy, and positive surgical margins were all negatively correlated with overall survival. The number of LNs removed and lobectomy/bilobectomy correlated with improved survival. The removal of <10 LNs was associated with a 12 % increased risk of death (HR: 1.12, 95 % CI 1.09-1.14; p < 0.001). Conclusion. Survival of early-stage NSCLC patients is associated with the number of LNs removed. The surgical management of early-stage NSCLC should include thoracic lymphadenectomy of at least 10 nodes.