Molecular characterization and diagnostic yield of semirigid thoracoscopy in malignant pleural effusions of pulmonary origin

Molecular characterization of non-small-cell lung cancer is becoming increasingly important with the appearance of molecular testing. Tumors with somatic mutations in the gene that encodes for the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) or in the gene that encodes for the anaplastic lymphoma kinase (ALK) preclude favorable responses to tyrosine kinase and ALK inhibitors, respectively. Semirigid thoracoscopy is a minimally invasive technique for pleural effusion management. However, there is scarce evidence assessing the role of semirigid thoracoscopy for molecular testing, with only one study including EGFR mutation status but no study analyzing ALK translocation. The aim of this prospective study was to evaluate the adequacy of samples obtained using semirigid thoracoscopy for EGFR mutation and ALK translocation analyses in confirmed primary lung cancers. We conducted a prospective analysis of 26 consecutive patients referred for semirigid thoracoscopy between November 2009 and July 2015. Twenty-two cases were adenocarcinomas. Fourteen samples were sent for molecular analysis. Semirigid thoracoscopy had a diagnostic yield of 95.45%for malignancy. EGFR mutation testing was possible in all (100%) cases. EGFR mutations were detected in 2/14 (14.2%) samples. ALK translocation testing was possible in all but one (90%), although negative in all of them. This study confirms the high clinical utility of samples obtained through semirigid thoracoscopy for EGFR and ALK genotyping in primary lung cancers.