Introduction Epidermal growth factor receptor (EGFR) gene mutations in non-small cell lung cancer have been shown to confer improved responsiveness to tyrosine kinase inhibitors. NICE recommends tyrosine kinase inhibitors as first line therapy in patients with locally advanced or metastatic tumours with EGFR gene mutations. Evidence from a multicentre retrospective study of 119 patients undergoing EBUS-TBNA to obtain cell block samples showed that EGFR mutation analysis was possible in 89.9% (107/119)1. Similar results 32/36 (88.8%) have been observed in a smaller more recent study2. The aim of this single centre prospective study was to evaluate the adequacy of EBUS-TBNA histology specimens using both 21G and 22G needles in confirmed primary lung adenocarcinoma.
Methods A prospective analysis was performed on 250 consecutive patients undergoing EBUS-TBNA between 2009 and 2013. 21G or 22G needles (Olympus ViziShot, NA-201SX-4021 and NA-201SX-4022) were used by operator discretion. A minimum of 2 passes were carried out per nodal station. Samples were fixed in formalin and prepared for histopathological analysis. The proportion of confirmed primary lung adenocarcinoma samples in which EGFR mutation testing was feasible was determined.
Results Primary lung adenocarcinoma was confirmed in 45 patients (18%). EGFR mutation analysis was attempted in 35 of these patients and was possible in 34 (97.1%). EGFR mutation was present in 3 patients (8.8%).
Conclusions This single centre study demonstrates both 22G and 21G EBUS-TBNA samples are adequate for EGFR mutation analysis with no clear superiority in contrast to recent data suggesting disease phenotyping may be superior using a 21G needle when analysed by histopathology. We speculate that higher sample usability rates for mutation analysis may have been facilitated by the use of histological specimens however further larger studies are required to confirm this hypothesis.
Navani N, Brown JM, Nankivell M et al. Suitability of endobronchial ultrasound-guided transbronchial needle aspiration specimens for subtyping and genotyping of non-small cell lung cancer: a multicentre study of 774 patients. AJRCCM (2012); 185(12): 1316–22
Esterbrook G, Anathhanam S, Plant PK. Adequacy of endobronchial ultrasound transbronchial needle aspiration samples in the subtyping of non-small cell lung cancer. Lung Cancer (2013); 80(1): 30–4.