Prospective evaluation of EBUS-TBNA specimens for programmed death-ligand 1 expression in non-small cell lung cancer patients: a pilot study

Objective: EBUS-TBNA cytological sampling is routinely performed for pathological diagnosis, mediastinal staging, and molecular testing in lung cancer patients. EBUS-TBNA samples are not formally accepted for testing programmed death-ligand 1 (PD- L1) expression. The objective of the study was to compare the feasibility, reproducibility, and accuracy of PD- L1 expression assessment in cytological specimens and histological samples. Methods: We prospectively collected histological (transbronchial forceps biopsy) and cytological (EBUS-TBNA) samples from peribronchial neoplastic lesions during an endoscopic procedure at the same target lesion for the pathological diagnosis and molecular assessment of stage IV non-small cell lung cancer (NSCLC). Results: Fifteen patients underwent the procedure. Adequate cytological samples (at least 100 neoplastic cells) were obtained in 12 cases (92.3%). Assessment of PD-L1 expression was similar between histological and cytological samples (agreement rate = 92%). Sensitivity and diagnostic accuracy of EBUS-TBNA cytological specimens were 88.9% and 100%, respectively. Conclusions: The evaluation of PD-L1 expression in EBUS-TBNA cytological specimens is feasible and presents good reproducibility when compared with routine histological samples. EBUS-TBNA cytological samples could be used for the assessment of PD- L1 expression in patients with NSCLC as a minimally invasive approach in stage IV NSCLC cancer patients.