Pilot Study of the Performance of 19-G Needle in Endobronchial Ultrasound-guided Transbronchial Aspiration for the Diagnosis and Testing of Molecular Markers in Lung Cancer

Background: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has become the standard for diagnosis and staging of lung cancer. Historically, 21-and 22-G needles have been paired with EBUS. We evaluated the performance of EBUS-TBNA using a larger 19-G needle in the assessment of tumor tissue obtained and success of testing for molecular markers. Methods: We prospectively enrolled adult patients with lymphadenopathy concerning for metastatic lung cancer. Patients underwent diagnostic EBUS-TBNA utilizing 19-G needles. Cases of non-small cell lung cancer (NSCLC) were evaluated for programmed cell death receptor ligand (PD-L1) expression. Cases of adenocarcinoma or undifferentiated NSCLC were further evaluated for 3 molecular markers for driver mutations: epidermal growth factor receptor (EGFR), c-ros oncogene 1 (ROS-1), and anaplastic lymphoma kinase (ALK). Results: Fifty patients were enrolled and underwent EBUS-TBNA using 19-G needles. PD-L1 assay was successfully performed in 90% of NSCLC cases. In adenocarcinoma or undifferentiated NSCLC cases, the success rate in testing was 90% for EGFR and 86% for ALK. ROS-1 testing had a success rate of 67%; 24% of these specimens had adequate tumor cells but there was technical difficulty with the assay. Block quality was judged by total number of tumor cells per hematoxylin and eosin-stained slide of each cell block (58% of specimens had >500 cells and 22% had 200 to 500 cells). There were no adverse events. Conclusion: EBUS-TBNA using 19-G needles can obtain a high number of tumor cells and has a high rate of success in performing assays for PD-L1, EGFR, and ALK in NSCLC patients without an increase in adverse events. The success rate of ROS-1 testing was lower.