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.
Submitted February 12, 2020; accepted for publication August 6, 2020. Published online January 28, 2021.
Author contributions: Study concept and design: D. Chen, Mao, Wen, Xue, Fan, Y. Chen, C. Chen. Data acquisition: Shu, Ye, She, Ding, Shi, Xue. Data analysis and interpretation: D. Chen, Mao, Wen. Manuscript preparation: D. Chen, Mao, Wen, Shu, Ye, She, Ding, Shi. Critical revision: Xue, Fan, Y. Chen, C. Chen. Supervision: Fan, Y. Chen, C. Chen.
Disclosures: The authors have disclosed that they have not received any financial consideration from any person or organization to support the preparation, analysis, results, or discussion of this article.
Funding: This work was supported by projects from the Shanghai Hospital Development Center (SHDC12015116); the National Natural Science Foundation of China (81802256); the Science and Technology Commission of Shanghai Municipality (15411968400 and 14411962600); the Suzhou Key Laboratory of Thoracic Oncology (SZS201907); the Suzhou Key Discipline for Medicine (SZXK201803); the Municipal Program of People’s Livelihood Science and Technology in Suzhou (SS2019061); Jiangsu Key Research and Development Plan (Social Development) Project (BE2020653); and Clinical Research Plan of Shanghai Hospital Development Center (SHDC2020CR3025B).