Impact of Lymph Node Metastasis Patterns on Long-Term Survival in Upper Lobe Non-Small Cell Lung Cancer

OBJECTIVES: While treatment strategies for non-small cell lung cancer (NSCLC) continue to evolve, the prognostic implications of lymph node metastasis patterns in upper lobe tumours remain inadequately defined. This study investigated whether tumour laterality and specific nodal stations involved in N2a disease correlate with long-term survival in patients undergoing surgical resection for upper lobe NSCLC. METHODS: This retrospective single-centre study included patients with stage I-IIIB upper lobe NSCLC who underwent anatomical resection with systematic lymph node dissection from January 2010 to December 2022. Patients were stratified by tumour laterality and nodal involvement, with specific analysis of N2a subgroups based on lymph node station. Propensity score matching, Kaplan-Meier survival analysis, and log-rank testing were used to compare survival outcomes. RESULTS: Of 3313 patients considered, 2028 met the prespecified inclusion criteria (right: n = 1212; left: n = 816). Mean age was 65.7 ± 9.4 years; 61.7% were male. Median overall survival (OS) was similar for right- and left-sided N0 and N1 tumours. Significant differences emerged among N2a subgroups: Patients with left-sided skip metastases to LN5/6 had markedly improved OS (66.2 ± 14.9 months) versus right-sided LN2/4 (35.3 ± 8.5 months; P = .047). Outcomes of left-sided N2a1 LN5/6 were also more favourable than LN7-9 (37.7 ± 15.2 months; P = .023) and showed better OS than left-sided N1 disease (47.6 ± 4.2 months; P = .284). CONCLUSIONS: Positive nodal station and tumour laterality significantly impact survival in upper lobe NSCLC. Skip metastases to LN5/6 in left-sided tumours were linked to more favourable prognosis and may warrant inclusion in future TNM classification refinements.