Performance of Endobronchial Ultrasound Transbronchial Needle Aspiration as the First Nodal Staging Procedure for the Determination of Programmed Death Ligand-1 Expression in Non-Small Cell Lung Cancer Patients

Purpose: The determination of the Programmed Death Ligand-1 ( PD-L1) expression is part of the diagnostic algorithm for advanced non-small-cell lung cancer (NSCLC) patients. We aimed to analyze the diagnostic performance of EBUS-TBNA performed as first-choice nodal staging procedure for the determination of PD-L1 expression in NSCLC patients. Methods: Longitudinal-prospective study including NSCLC patients diagnosed between January 2018 and October 2019, for whom a primary tumor biopsy sample and an EBUS-TBNA cytological malignant sample were available. Samples with fewer than 100 malignant cells were considered inadequate. PDL-1 IHC 22C3 pharmDx antibody was used. The percentage of tumor cells expressing PD-L1, setting 1% and 50% as cutoff points, was collected. The weighted kappa coefficient was used to assess the concordance of PD-L1 expression. The PD-L1 expression was compared precision terms. Results: From a total of 43 patients, 53 pairs of samples were obtained, of which 23 (43.4%) were adequate and included for analysis. The weighted kappa coefficient for PD-L1 expression was 0.41 (95% CI: 0.15–0.68) and 0.56 (95% CI: 0.23–0.9) for cutoff values ≥ 1% and ≥ 50%, respectively. In advanced stages, the weighted kappa coefficient was 0.6 (95% CI: 0.3–0.9) and 1 (95% CI: 1–1) for PD-L1 expression cutoff values ≥ 1% and ≥ 50%, respectively. EBUS-TBNA showed a sensitivity, specificity, positive predictive value, and negative predictive value of 1 to detect PDL-1 expression ≥ 50% in advanced stages. Conclusion: EBUS-TBNA performed as first nodal staging procedure provides reliable specimens for the detection of PD-L1 expression ≥ 50% in advanced NSCLC patients and could guide immunotherapy.