Introduction: Stage III/N2 Non-small cell lung cancer (NSCLC) is a complex disease with multi-modality therapeutic options. UK practice emphasizes the presence of single station N2 (ssN2) vs multi-station N2 disease (msN2) to determine treatment. A pilot study in Manchester, found 34% of patients with pre-operative ssN2 disease (based on CT, PET-CT and EBUS) were upstaged at pathological sampling (Craig, C. et al. Lung cancer, v156, S23).  This study aims to investigate this correlation across multiple centres.

Methods:We conducted a retrospective analysis across 6 UK sites over a 5-year period (01/01/2016-31/12/2020). Data was collected from patients with T1-4N2M0 NSCLC, who had pre-operative staging (CT, PET and EBUS-TBNA) and an MDT diagnosis of ssN2, who underwent surgical resection. Clinical and pathological staging was compared to describe the diagnostic accuracy of pre-operative staging. Statistical analysis was performed on variables between the 2 groups. 

Results: 59 patients were recruited, 19 (32%) had pathological staging of msN2. 37% of these patients had no evidence of N2 nodes on CT but 89% had a PET stage of ssN2. In the false ssN2: 58% had nodes not sampled due to EBUS characteristics and size, 4 were due to negative EBUS sampling and 4 due to inaccessible nodes. There was no statistically significant difference in tumour sub-typing, location, size or PET-SUV between the 2 groups. Median time from EBUS to surgery was 33 days.

Conclusion: In stage III-N2 disease, pre-operative staging is unreliable at distinguishing between ssN2 and msN2 when compared to pathological stage. This should provide caution for centres which rely on this distinction to define treatment.