Gunizi, Ozlem CerenGunizi, Huseyin2026-01-242026-01-2420232074-18042074-1812https://doi.org/10.32592/ircmj.2023.25.6.2567https://hdl.handle.net/20.500.12868/5363Background: 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.eninfo:eu-repo/semantics/openAccessCarcinomaHead and neck cancerOral lichen planusPD-L1Precancerous lesionsArticle10.32592/ircmj.2023.25.6.2567256WOS:001055472400007Q3