Numbers and Stations: Impact of Examined Lymph Node on Precise Staging and Survival of Radiologically Pure-Solid Non–Small Cell Lung Cancer

Abstract

Purpose: To determine the optimal number of examined lymph nodes (ELN) and that of examined node stations (ENS) in patients with radiologically pure-solid non-small cell lung cancer (NSCLCs), and to investigate the impact of ELN and ENS on accurate staging and long-term survival.

Methods: Data from six institutions in China on resected c-stageⅠ-Ⅱ NSCLCs presenting as pure-solid tumors were analyzed for the impact of ELN and ENS on nodal upstaging, stage migration, recurrence-free survival (RFS) and overall survival (OS) by using multivariate models. The correlations between different endpoints and ELN or ENS were fitted with a LOWESS smoother, and the structural break points were determined by Chow test.

Results: Both ELN and ENS were identified as prognostic factors for OS (ENS: HR, 0.697; 95%CI: 0.590 to 0.824; P < 0.001; ELN: HR, 0.945; 95%CI: 0.909 to 0.983; P = 0.005) and RFS (ENS: HR, 0.863; 95%CI: 0.791 to 0.941; P = 0.001; ELN: HR, 0.960; 95%CI: 0.938 to 0.981; P < 0.001). Intraoperative ELN and ENS were found to be associated with postoperative nodal upstaging. Cut point analysis revealed an optimal cutoff of 16 LNs and 5 node stations for c-stageⅠ-Ⅱ pure-solid NSCLCs patients, which were examined in our multi-institutional cohort.

Conclusion: Both ELN and ENS are associated with more-accurate node staging and better long-term survival. We recommend 16 LNs and 5 stations as the cut point for evaluating the quality of LN examination for c-stageⅠ-Ⅱ patients with radiologically pure-solid NSCLCs.