Multicentric evaluation of the impact of central tumour location when comparing rates of N1 upstaging in patients undergoing video-assisted and open surgery for clinical Stage I non-small-cell lung cancer

Large retrospective series have indicated lower rates of cN0 to pN1 nodal upstaging after video-assisted thoracic surgery (VATS) compared with open resections for Stage I non-small-cell lung cancer (NSCLC). The objective of our multicentre study was to investigate whether the presumed lower rate of N1 upstaging after VATS disappears after correction for central tumour location in a multivariable analysis. Consecutive patients operated for PET-CT based clinical Stage I NSCLC were selected from prospectively managed surgical databases in 11 European centres. Central tumour location was defined as contact with bronchovascular structures on computer tomography and/or visibility on standard bronchoscopy. Eight hundred and ninety-five patients underwent pulmonary resection by VATS (n = 699, 9% conversions) or an open technique (n = 196) in 2014. Incidence of nodal pN1 and pN2 upstaging was 8% and 7% after VATS and 15% and 6% after open surgery, respectively. pN1 was found in 27% of patients with central tumours. Less central tumours were operated on by VATS compared with the open technique (12% vs 28%, P < 0.001). Logistic regression analysis showed that only tumour location had a significant impact on N1 upstaging (OR 6.2, confidence interval 3.6-10.8; P < 0.001) and that the effect of surgical technique (VATS versus open surgery) was no longer significant when accounting for tumour location. A quarter of patients with central clinical Stage I NSCLC was upstaged to pN1 at resection. Central tumour location was the only independent factor associated with N1 upstaging, undermining the evidence for lower N1 upstaging after VATS resections. Studies investigating N1 upstaging after VATS compared with open surgery should be interpreted with caution due to possible selection bias, i.e. relatively more central tumours in the open group with a higher chance of N1 upstaging.