Adherence to the mediastinal staging guideline and unforeseen N2 disease in patients with resectable non-small cell lung cancer: Nationwide results from the Dutch Lung Cancer Audit - Surgery.

Objectives: Invasive mediastinal staging is advised by guidelines in patients with resectable non-small cell lung cancer (NSCLC) and suspicious lymph nodes (cN1-3) or for central, FDG-non-avid or peripheral tumours >3 cm. Our objective was to assess current guideline adherence and consequent unforeseen N2 disease (uN2) in NSCLC patients having various indications for mediastinal staging.

Materials And Methods: We analysed the Dutch Lung Cancer Audit - Surgery data of all patients who underwent a primary lung resection with lymph node dissection for NSCLC in 2017-2018. Based on the 2015 ESTS-ERS-ESGE guideline we assessed the use of initial endosonography and confirmatory mediastinoscopy as well as uN2 rates.

Results: A total of 2238 patients were analysed. 43 % (95 %-CI: 41-45) underwent initial endosonography followed by a confirmatory mediastinoscopy in 44 % (95 %-CI:40-47) of them, resulting in a 19 % (95 %-CI: 17-20) rate of properly staged patient according to the guidelines. uN2 was demonstrated in 12.5 % (95 %-CI: 9.7-16.0) of correctly staged patients compared to 10.9 % (95 %-CI: 9.6-12.4) who were not (p = .36). The highest uN2 rate was found in cN1-3 patients who were not staged (23.0 %, 95 %-CI: 16.4-31.2) compared to 13.0 % (95 %-CI: 9.7-17.1) who were (p = .01).

Conclusion: Guideline adherence in Dutch NSCLC patients with an indication for invasive mediastinal staging is poor. The highest uN2 rate was found in unstaged cN1-3 patients, suggesting that this subgroup may benefit from an appropriate staging conform guidelines.