Assessment of Programmed Cell Death Ligand-1 Expression in Non-small Cell Lung Carcinomas by Immunohistochemistry

Non-small cell lung carcinomas (NSCLCs) expressing programmed cell death ligand-1 (PD-L1), a transmembrane protein, are more likely to respond to immunotherapy drugs. All advanced NSCLC samples should be examined with PD-L1 immunohistochemistry (IHC). PD-L1 is now the only approved predictive biomarker of immunotherapy response in NSCLC patients. This study evaluates the expression of PD-L1 in NSCLC by IHC and assesses the morphological and clinical correlation of PD-L1 expression. All patients with histologically proven NSCLC with needle core biopsies and resected specimens were analyzed in the department of pathology. The correlation of PD-L1 expression with morphological and clinical parameters was analyzed. On evaluating PD-L1 expression in 97 cases of NSCLC, 61.85% (n = 60) had positive PD-L1 staining. Among patients with a positive tumor proportion score, 22 had a history of smoking, 51 were ≥50 years old, 43 were male patients, 24 were in Stage IV, 44 had a history of chemotherapy or radiotherapy, 47 had adenocarcinoma, and 33 had Grade II tumors. The association of PD-L1 expression with various clinicopathological parameters such as gender, smoking status, histological type, histological grade, clinical tumor stage, previous treatment history, site and type of biopsy, necrosis, and peritumoral lymphoid response was not statistically significant. Our study indicated that PD-L1 expression was not associated with various clinicopathological variables in NSCLC. More research is needed to look into the probable factors that influence the PD-L1-positive distribution. Since expression of the PD-L1 protein is proven to be of therapeutic and prognostic significance, we recommend that testing for PD-L1 should be done at least in cases of advanced-stage NSCLC.