Prognostic Relevance of Negative Lymph Node Count in Resected Stage I–IIIa Small-cell Lung Cancer

Abstract

Objectives: The prognostic significance of the negative lymph node (NLN) count has been confirmed in various cancers but not in small-cell lung cancer (SCLC). We aimed to evaluate the correlation between the NLN count and the prognosis of patients with stages I–IIIa SCLC who underwent lobectomy. Methods: Data on the clinical characteristics of SCLC patients who underwent lobectomy between 2000 and 2019 were collected from the SEER database and organized based on the X-tile plots to identify the optimal cutoff point for the NLN count. Kaplan–Meier curves and a Cox proportional hazard model were used to evaluate the prognostic factors for overall survival (OS) and lung cancer-specific survival. Results: Based on the X-tile plot-determined cutoff points of 3 and 7, the participants were grouped into the low (<3), middle (3–7), and high (>7) NLN subgroups for the analysis of OS. Univariable analysis showed that a higher NLN count correlated with more favorable OS and lung cancer-specific survival (both P<0.001). Multivariate analysis demonstrated that, after adjustment for related factors, the NLN count was positively associated with the prognosis and might thus be an independent risk factor for prognosis. Subgroup analyses revealed that, among different LN statuses and varied positive LN counts, the NLN count could predict the prognosis independently. Conclusions: Higher NLNs correlated with better survival for patients who underwent lobectomy of stages I–IIIa SCLC. A predictive marker that combines the NLN count with the N stage and positive LN count could provide more prognostic information in SCLC.