Cytology cell blocks from malignant pleural effusion are good candidates for PD-L1 detection in advanced NSCLC compared with matched histology samples

Detection of programmed cell death ligand-1 (PD-L1) by immunohistochemistry (IHC) has been commonly used to predict the efficacy of treatment with PD-1/PD-L1 inhibitors. However, there is limited literature regarding the reliability of PD-L1 testing using malignant pleural effusion (MPE) cell blocks.