PDL1 and IDO-2 Immunohistochemistry in Bronchoalveolar Lavage Versus Bronchoscopic Biopsy of Non-Small Cell Lung Cancer.

[OBJECTIVES] Cytology specimens are less invasive than tissue biopsies, and in some cases of non-small cell lung cancer (NSCLC), they may be the only available material. The expression of programmed death ligand-1 (PD-L1) and indoleamine 2-3 dioxygenase 2 (IDO-2) predicts the response to new treatment modalities. The aim of the study was to investigate the validity of cell blocks prepared from cytology for evaluation of PD-L1 and IDO-2 expression in NSCLC and to compare the expression of these markers in cell blocks and the corresponding tissue sample.

[MATERIAL] This cross-sectional study included 32 specimens of bronchoalveolar lavage (BAL) cytology and their cell block preparations. Among them, 20 cases also had bronchoscopic biopsy. PD-L1 and IDO-2 immune staining were done for all cases.

[RESULTS] A statistically significant association is observed between high PD-L1 expression and both tumour size (p = 0.00014) and grade (p = 0.00001). High IDO-2 expression is associated with low TILs (p = 0.03). Results of PD-L1 and IDO-2 expression in bronchoscopic biopsy and cell block preparations of the same cases showed no statistical difference (p = 0.246).

[CONCLUSION] There was no significant difference in PD-L1 and IDO-2 expression between cytological and bronchoscopic biopsies of lung cancer, which supports the effective use of cytological specimens and reduces the need for more invasive procedures.