PD‐L1 expression in non‐small cell lung carcinoma: Comparison among cytology, small biopsy, and surgical resection specimens

BACKGROUND One immunotherapeutic agent for patients with advanced non‐small cell lung carcinoma, pembrolizumab, has a companion immunohistochemistry (IHC)‐based assay that predicts response by quantifying programmed death‐ligand 1 (PD‐L1) expression. The current study assessed the feasibility of quantifying PD‐L1 expression using cytologic non‐small cell lung carcinoma specimens and compared the results with those from small biopsy and surgical...