Abstract
BACKGROUND: The prognostic significance of skip metastasis remains controversial in the context of the recently revised N2a (single-station) and N2b (multi-station) of non-small cell lung cancer (NSCLC). This study aims to investigate the survival impact of skip metastasis in these subgroups. METHODS: We retrospectively analyzed 1,873 NSCLC patients who underwent surgery with systematic lymph node dissection at a single institution. Patients were categorized into pN1, skip pN2a, non-skip pN2a, skip pN2b, and non-skip pN2b groups. Overall survival (OS) and disease-free survival (DFS) were assessed using Kaplan-Meier analysis and Cox proportional hazards regression, with propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) applied to minimize confounding. RESULTS: Skip metastasis was identified in 34.1% of pN2 cases, with a higher incidence in pN2a (41.3%) than in pN2b (24.3%). Skip pN2a showed significantly better 5-year OS and DFS rates compared to non-skip pN2a (72% vs. 67%, P=0.02; 57% vs. 48%, P=0.002). Similarly, skip pN2b had superior outcomes compared to non-skip pN2b (5-year OS: 65% vs. 58%, P=0.008; DFS: 42% vs. 37%, P=0.03). Notably, no significant survival difference was observed between skip pN2a and pN1, or between non-skip pN2a and skip pN2b, even after PSM and IPTW adjustments. CONCLUSIONS: Skip metastasis confers a survival advantage in both pN2a and pN2b NSCLC subgroups with comparable survival between skip pN2a and pN1, as well as between non-skip pN2a and skip pN2b.