Lymph node dissections and survival in sublobar resection of non-small cell lung cancer ≤ 20 mm

Background: A randomized trial of lobectomy versus segmentectomy for small-sized (≤ 20 mm) non-small cell lung cancer (NSCLC) showed that patients who had undergone segmentectomy had a significantly longer overall survival (OS) than those who had lobectomy. More attention is needed regarding the required extent of thoracic lymphadenectomy in patients with small-sized NSCLC who undergo sublobar resection. Methods: The National Cancer Database was queried for patients with clinically node-negative NSCLC ≤ 20 mm who had undergone sublobar resection between 2004 and 2017. OS of NSCLC patients by the number of lymph node dissections (LNDs) was analyzed using log-rank tests and Cox proportional hazards model. The cutoff value of the LNDs was set to 10 according to the Commission on Cancer’s recommendation. Results: This study included 4379 segmentectomy and 23,138 wedge resection cases. The sequential improvement in the HRs by the number of LNDs was evident, and the HR was the lowest if the number of LNDs exceeded 10. Patients with ≤ 9 LNDs had a significantly shorter OS than those with ≥ 10 LNDs (hazard ratio [HR] 1.50, 95% confidence interval [CI] 1.40–1.61, P < 0.0001). Multivariable analysis revealed that performing ≤ 9 LNDs was an independent factor for predicting OS (HR for death: 1.34, 95% CI 1.24–1.44, P < 0.0001). These results remained significant in subgroup analyses by the type of sublobar resection (segmentectomy, wedge resection). Conclusions: Performing ≥ 10 LNDs has a prognostic role in patients with small-sized NSCLC even if the resection is sublobar.