Prognostic Significance of Programmed Death-Ligand 1 Expression in Betel Nut Chewing Patients with Oral Squamous Cell Carcinoma

Objective: This study aimed to investigate the prognostic significance of programmed death-ligand 1 (PD-L1) expression in Taiwanese patients with oral squamous cell carcinoma (OSCC) who underwent surgical treatment, particularly in those with a history of betel-nut chewing. Materials and Methods: We retrospectively analyzed the medical records of patients with OSCC diagnosed and treated at a single tertiary hospital between 2017 and 2023. Immunohistochemical evaluation of formalin-fixed, paraffin-embedded tumor specimens was performed using the validated anti–PD-L1 antibody clone 22C3. PD-L1 expression was evaluated using the Combined Positive Score (CPS), and CPS≥1 and ≥20 were defined as PD-L1 positivity and overexpression, respectively. An additional score was obtained by subtracting the CPS from the Tumor Proportion Score (TPS) to clarify the effect of the immune cells. The associations between PD-L1 expression and overall survival (OS), and disease-free survival were assessed using Kaplan–Meier and Cox regression analyses. Results: Of the 118 OSCCs, 56.8% and 31.4% exhibited PD-L1 positivity and overexpression, respectively. PD-L1 overexpression and TPS-CPS≥10 were significantly associated with improved OS ( p =0.022 and p =0.035, respectively). Multivariate analysis confirmed that PD-L1 overexpression and cancer stage were independent prognostic factors for OS ( p =0.010 and p =0.001, respectively). However, PD-L1 overexpression was not significantly correlated with tumor stage, primary site, or adverse pathological features. Conclusion: High PD-L1 expression is a favorable prognostic biomarker in patients with surgically treated OSCC, particularly in populations with prevalent betel nut use. These findings suggest that PD-L1 expression can guide immunotherapy decisions and risk stratification in OSCC management. Clinical relevance : Patients with OSCC exhibiting high PD-L1 expression have a better survival rate after surgery. PD-L1 testing may help in risk stratification and guiding immunotherapy decisions.