Evaluation of programmed death ligand 1 expression in cytology to determine eligibility for immune checkpoint inhibitor therapy in patients with head and neck squamous cell carcinoma.

PD-L1 expression in HNSCC cytology samples has high concordance with paired histologic samples. PD-L1 CPS evaluation is feasible in HNSCC cytology CBs and can act as a surrogate for determining eligibility for immunotherapy in cases in which a histologic specimen is not readily available.