Prognostic significance of programmed death-ligand 1 expression in betel nut chewing patients with oral squamous cell carcinoma

This study aimed to evaluate the prognostic significance of programmed death-ligand 1 (PD-L1) expression in Taiwanese patients with oral squamous cell carcinoma (OSCC) who underwent surgical treatment and had a history of betel-nut chewing. 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). CPS ≥ 1 and ≥ 20 were defined as PD-L1 positivity and overexpression, respectively. An additional score was obtained by subtracting the tumor proportion score (TPS) from the combined positive score (CPS) to clarify the effect of the immune cells. The associations between PD-L1 expression, overall survival (OS), and disease-free survival (DFS) were assessed using Kaplan–Meier and Cox regression analyses. Of the 118 OSCCs, 56.8% and 31.4% exhibited PD-L1 positivity and overexpression, respectively. PD-L1 overexpression and CPS-TPS ≥ 10 were significantly associated with improved OS (p = 0.023 and p = 0.035, respectively). Multivariate analysis confirmed that PD-L1 overexpression and cancer stage were independent prognostic factors for OS (p = 0.031 and p = 0.000, respectively). However, PD-L1 overexpression was not significantly correlated with tumor stage, anatomical site, or adverse pathological features. 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. 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.