Impact of the Extent of Lymph Node Dissection on Precise Staging and Survival in Clinical I–II Pure-Solid Lung Cancer Undergoing Lobectomy

Abstract

Background: This study sought to determine the optimal number of examined lymph nodes (ELNs) and examined node stations (ENSs) in patients with radiologically pure-solid non–small cell lung cancer (NSCLC) who underwent lobectomy and ipsilateral lymphadenectomy by investigating the impact of ELNs and ENSs on accurate staging and long-term survival. Materials and Methods: Data from 6 institutions in China on resected clinical stage I–II (cI–II) NSCLCs presenting as pure-solid tumors were analyzed for the impact of ELNs and ENSs on nodal upstaging, stage migration, recurrence-free survival (RFS), and overall survival (OS). Correlations between different endpoints and ELNs or ENSs were fitted with a LOWESS smoother, and the structural break points were determined by Chow test. Results: Both ELNs and ENSs were identified as independent prognostic factors for OS (ENS hazard ratio [HR], 0.690; 95% CI, 0.597–0.797; P<.001; ELN HR, 0.950; 95% CI, 0.917–0.983; P=.004) and RFS (ENS HR, 0.859; 95% CI, 0.793–0.931; P<.001; ELN HR, 0.960; 95% CI, 0.942–0.962; P<.001), which were also associated with postoperative nodal upstaging (ENS odds ratio [OR], 1.057; 95% CI, 1.002–1.187; P=.004; ELN OR, 1.186; 95% CI, 1.148–1.226; P<.001). A greater number of ELNs and ENSs correlated with a higher accuracy of nodal staging and a lower probability of stage migration. Cut-point analysis revealed an optimal cutoff of 18 LNs and 6 node stations for stage cI–II pure-solid NSCLCs, which were validated in our multi-institutional cohort. Conclusions: Extensive examination of LNs and node stations seemed crucial to predicting accurate staging and survival outcomes. A threshold of 18 LNs and 6 node stations might be considered for evaluating the quality of LN examination in patients with stage cI–II radiologically pure-solid NSCLCs.