Does Lymph Node Count Influence Survival in Surgically Resected Non-Small Cell Lung Cancer?

Background. The prognostic significance of the number of lymph nodes sampled (NLNS) during resection for non-small cell lung cancer (NSCLC) is unclear. The NLNS is influenced by many factors, and some have argued that it should be a surrogate for quality. We sought to determine the influence of the NLNS on overall survival and cancer-specific survival for surgically resected NSCLC. Methods. The California Cancer Registry was queried from 2004 to 2011 for cases of stage I to III NSCLC treated with surgical resection, identifying 16,393 patients. Kaplan-Meier and Cox proportional hazards modeling were used to determine the influence of NLNS on overall survival and cancer-specific survival. Results. In all, 15,195 patients had information regarding nodal sampling. Eighty percent (13,167 of 15,195) were treated with lobectomy. Patients who were younger, male, non-Hispanic white, highest socioeconomic status, higher stage, or larger size tumor had more nodes removed. Sampling fewer than 10 nodes was associated with poorer overall survival when compared with sampling 10 or more nodes after adjustment for demographic and clinical factors for stage I: overall survival hazard ratio 1.78 (95% confidence interval: 1.54 to 2.05, p < 0.0001), hazard ratio 1.43 (95% confidence interval: 1.27 to 1.59, p < 0.0001), and hazard ratio 1.16 (95% confidence interval: 1.05 to 1.28, p = 0.004), for 0, 1 to 3, and 4 to 10 nodes, respectively. Of patients who underwent sublobar resection, 43.8% had no nodes sampled. Conclusions. For NSCLC, the NLNS influenced both overall survival and cancer-specific survival, but the influence is dependent on stage. Surgeons should perform mediastinal lymphadenectomy to maximize patient survival, but the optimal NLNS remains unclear. (C) 2017 by The Society of Thoracic Surgeons