Evaluation of the Presence and Importance of PD-L1 Expression in Head-neck Squamosus Cell Carcinomas and Premalign Lesions

Background: Programmed Death-Ligand 1 (PD-L1) is a cell membrane protein found on the surface of cancer cells, immune system cells in the tumor microenvironment, and various healthy tissues. Moreover, it plays a key role in suppressing the immune system. Objectives: We aim to explain the presence of PD-L1 in Head-Neck Squamosus Cell Carcinomas (HNSCC) and premalign lesions by immunohistochemical method. Methods: Our retrospective study included 22 patients with HNSCC (15(68.1%) Oral cavity and 7(31.9%) Oropharynx), 20 patients with oral lichen planus, and 14 patients with normal oral cavity mucosa. In the evaluation of PD-L1 antibodies applied immunohistochemically in patients with HNSCC, the percentage of tumor cells showing membranous staining with PD-L1 antibodies was calculated. Results: The mean age of HNSCC patients participating in the study was 52.24 ± 11.7 years, the mean age of oral lichen planus patients was 34.10 ± 9.8 years, and the control patients' mean age was 31.42 ± 10.6 years. The rate of PD-L1 staining of tumor cells of HNSCC patients was significantly higher than the control group (P=0.001). Conclusion: The importance of PD-L1 expression in HNSCC and precancerous lesions of the oral cavity is remarkable, and the values may be related to the pathophysiology of these diseases.