Expression of PD-L1 in head and neck squamous cell carcinoma and its correlation with HPV status: a clinicopathological study

Abstract Background Head and neck squamous cell carcinoma (HNSCC) is a major global health concern with high morbidity and mortality. Programmed death ligand-1 (PD-L1), an immune checkpoint protein, plays a key role in tumor immune evasion and has emerged as an important biomarker for immunotherapy. Human papillomavirus (HPV)-associated HNSCC represents a distinct subset with different biological behavior and prognosis. Objectives To evaluate PD-L1 expression in HNSCC and determine its correlation with HPV status and clinicopathological parameters. Materials and methods This hospital-based cross-sectional study included 100 histopathologically confirmed cases of HNSCC. PD-L1 expression was assessed by immunohistochemistry and scored using the Combined Positive Score (CPS). HPV status was evaluated using cobas HPV DNA testing and RNA in situ hybridization for E6/E7 mRNA. Statistical analysis was performed using the Chi-square test, with p < 0.05 considered significant. Results PD-L1 expression was observed in a substantial proportion of HNSCC cases. HPV DNA-positive tumors showed a higher frequency of PD-L1 expression compared to HPV DNA-negative tumors (73.8% vs 53.4%, p < 0.05). HPV DNA positivity was significantly associated with tumor site and histological grade. No statistically significant association was observed between PD-L1 expression and clinicopathological parameters, including age, gender, tumor stage, and histological grade. Conclusion PD-L1 expression showed a significant association with HPV DNA-positive status in HNSCC and may reflect an immune-active tumor microenvironment. However, given the cross-sectional design and use of a non-companion diagnostic PD-L1 assay, these findings should be interpreted as exploratory and require validation in larger studies using standardized PD-L1 testing platforms and clearly defined HPV status.