Objectives: Precise staging of non-small cell lung cancer (NSCLC) determines initial treatment and provides more accurate prognostic information for patients. The aim of this cohort study was to determine factors affecting pre- and post-operative mediastinal nodal staging agreement and its effect on 2-year survival.

Materials and Methods: A retrospective multi-centre cohort study was performed, using prospectively collected and pre-defined data from weekly lung cancer multidisciplinary team meetings in 11 hospitals.  Consecutive patients who underwent surgical resection of NSCLC between 2015 and 2017 were eligible. Factors associated with concordant and discordant pre- and post-operative nodal staging, and subsequent lung cancer-specific 2-year mortality were identified by univariate and multivariate regression.

Results: 973 patients fulfilled the eligibility criteria. Concordant pre- and post-operative nodal staging was observed in 783/973 (80%). 123/973 (13%) were under-staged pre-operatively. 67/973 (7%) were over-staged.In 173 patients with clinical N1 or N2 disease (in whom invasive mediastinal staging was indicated), staging EBUS was performed in 55/173 (32%). In these patients, younger age and use of staging EBUS were independent predictors of concordant pre- and post-operative staging.In all patients pre-operative under-staging was independently associated with increased lung cancer-specific 2-year mortality.

Conclusion: Invasive mediastinal staging with EBUS was independently associated with more accurate pre-operative staging. Pre-operative nodal under-staging was associated with increased lung cancer specific mortality. Nodal staging accuracy in potentially curable NSCLC is of fundamental importance to ensure patients receive the correct first-line treatment and to improve survival.