Impact of examined lymph node counts on survival of patients with stage IA non-small cell lung cancer undergoing sublobar resection

Background: The correlation between the number of examined lymph nodes (ELNs) and lung cancer-specific survival (LCSS) of stage IA non-small cell lung cancer (NSCLC) patients, who underwent sublobar resection in which lymph node (LN) sampling was relatively restricted as compared with standard lobectomy remains unclear. Methods: Patients from the Surveillance, Epidemiology, and End Results database with stage IA NSCLC who underwent sublobar resection were categorized based on ELN count (1-6 vs. >= 7; the cut point 7 was identified by Cox model). Results: Collectively, 3,219 patients with a median follow-up time of 37 months were included in this study (G1: 1-6 ELN, n=2,410; G2: >= 7 ELN, n=809). The 5-year LCSS rate of the G1 and G2 cohorts were 75% and 83%, respectively. Cox analysis suggested that the LCSS of G1 cohort patients was lower as compared with the G2 cohort [hazard ratio (HR) =1.530; 95% confidence interval (CI): 1.240-1.988, P<0.001). Propensity score analysis also showed decreased survival of the matched G1 cohort (HR =1.499; 95% CI: 1.176-1.911; P=0.001). Conclusions: The data suggested the ELNs >= 6 were associated with poor prognoses. Adequate LN sampling is essential even for stage IA NSCLC patients undergoing sublobar resection.