Performance of Endobronchial Ultrasound Transbronchial Needle Aspiration (EBUS-TBNA) with Rapid On-Site Evaluation (ROSE) in the pathological subtyping and molecular testing of non-small cell lung cancer (NSCLC) at a UK institute

Background: Differentiating NSCLC pathological subtypes as well as molecular testing is paramount to guide choice of chemotherapy and targeted EGFR and ALK therapies. The 2017 National Lung Cancer Audit( 1) highlighted the need to minimise the rate of NSCLC not otherwise specified (NSCLC-NOS). The objective of our study was to determine whether samples obtained by EBUS-TBNA in the presence of ROSE could be used to subtype NSCLC and provide sufficient material for molecular testing. Methods: A prospective database from a regional thoracic oncology centre was evaluated. All patients diagnosed with NSCLC by EBUS-TBNA cytology between January 2016 and January 2017 were included. Our institute performs reflex testing for EGFR and ALK on all adenocarcinoma or NSCLC-NOS cases. Results: A total of 128 patients were diagnosed with NSCLC via EBUS-TBNA. 11 were NSCLC-NOS (8.6%), 55 were squamous (43%), 56 adenocarcinoma (43.8%), 4 were large cell neuroendocrine (3.1%)and 2 were other NSCLC. 66 appropriate non-squamous lung cancer samples were sent for molecular analysis. For EGFR mutation, 62/66(94%) had sufficient material and 3 were positive (4.5%). For ALK, 63/66 (95%) had sufficient material and 2 (3%) were positive. Conclusions: Our study has illustrated EBUS-TBNA cytology with ROSE can achieve accurate subtyping of NSCLC and a high proportion of sufficient material for molecular analysis. In addition our NSCLC-NOS rate (8.6%)is lower than UK national average (9%) in 2017. References: 1- Royal College of Physicians. National Lung Cancer Audit annual report 2017