Prognostic value of human papilloma virus (HPV) status and programmed cell death ligand 1 (PD-L1) status in oral tongue cancer

Introduction: Despite advances in diagnostics and therapy, the 5-year mortality rate of oral squamous cell cancer (OSCC) remains at about 50%. Prognostic molecular biomarkers are not yet approved for clinical application, mainly due to conflicting results. The aim of our study was to determine the programmed cell death ligand 1 (PD-L1) status in oral tongue squamous cell carcinoma and their influence on patients' outcomes. Material and methods: Primary tumours were collected from 44 patients who underwent tumour surgical resection for primary OSCC from 2018 to 2022. Additionally demographic and clinical data were gathered. Results: Final analysis included patients with a mean age of 61 years (range 26-90), mostly males (n = 30, 68%). About half of the patients were treated in early local stage disease (T1-2, n = 21; 47%). There was no correlation between the mRNA level of PD-L1 and age of patients, smoking status, alcohol dependence, T stage, N stage, perineural invasion, lymphovascular invasion, extranodal extension, margin status, recurrence, and adjuvant treatment. PD-L1 expression was a key predictor variable of survival probability (HR = 0.5655, 95% CI = 0.3448-0.8851, p = 0.0118) - higher expression of PD-L1 was indicative of significantly improved overall survival. Kaplan-Meier analysis revealed a significantly better overall survival in patients with higher level of PD-L1. Conclusions: Patients with higher PD-L1 status in our study had better survival, which is contradictory to most of the published data. The reason for this may be the different detection method, and the examination of PD-L1 through mRNA is considered precise and repetitive. Studies with higher numbers of patients are needed to validate our conclusions.