Occult Hilar and Intrapulmonary Nodal Metastasis in Non-Small Cell Lung Cancer After Anatomical Resection

Backround: Hilar and pulmonary lymph node metastases are key determinants of prognosis in primary lung cancer. Despite advances in imaging and staging, the prognostic implications of N1 disease undetected during preoperative assessment remain poorly defined. This study evaluates patients with pathologically confirmed but preoperatively occult N1 metastases, focusing on survival outcomes and clinicopathological features, and explores their potential implications for prognostic stratification and future staging refinement. Methods: Data retrieved from 94 patients who underwent anatomical surgical resection for primary lung carcinoma between 2008 and 2024 and clinically, N0 were found to have N1 lymph node metastases on final pathology. Preoperative workup included both non-invasive and invasive staging. Results: Among patients with single-station N1 involvement, the 5-year disease-free survival (DFS) and overall survival (OS) rates were 53.2% and 59.7%, respectively — significantly better than those with multi-station disease (DFS: 17.8%, OS: 27.9%; p = p < 0.05 and p < 0.05). Stage IIA and IIB patients showed relatively favorable survival, while Stage IIIA patients had markedly poorer 5-year DFS and OS (p < 0.01). Univariate analysis confirmed that multi-station N1 involvement was associated with significantly worse prognosis, a finding that remained consistent in multivariate models as well. Conclusion: Multistation N1 involvement emerged as the strongest determinant of disease recurrence, while pleural invasion independently predicted overall survival. These findings indicate that unexpected N1 disease represents a biologically meaningful subgroup rather than a mere consequence of staging limitations and underscore the importance of detailed pathological nodal assessment for postoperative risk stratification and therapeutic decision-making. Occult Hilar and Intrapulmonary Nodal Metastasis in Non-Small Cell Lung Cancer After Resection Clinical trial number: not applicable.