Abstract
BACKGROUND: Pleural mesothelioma (PM) is an uncommon malignancy with a poor prognosis, even after surgical resection. Programmed death-ligand 1 (PD-L1) expression is a potential prognostic biomarker in various cancers, yet its role in PM patients undergoing pleurectomy/decortication (P/D) is unclear. This study aimed to evaluate the prognostic significance of PD-L1 expression in patients with PM who underwent P/D. METHODS: This retrospective study included patients with PM who underwent P/D from 2012 to 2022. PD-L1 expression in tumor cells was evaluated by immunohistochemistry, categorizing patients by tumor proportion score (TPS): 0%, 1-49%, and ≥50%. Survival outcomes were assessed using Kaplan-Meier curves and Cox proportional hazards regression models. RESULTS: A total of 58 patients were enrolled in the study. The median overall survival (OS) was 77.0 months for TPS 0%, 41.0 months for TPS 1-49%, and 25.3 months for TPS ≥50%. The corresponding relapse-free survival (RFS) was 34.3, 13.2, and 6.7 months, respectively. Lower PD-L1 expression was significantly associated with improved outcomes (OS: P=0.041, RFS: P=0.002). In multivariable analysis, PD-L1 TPS 0% (vs. ≥1%) emerged as an independent prognostic factor for RFS (hazard ratio, 0.37; 95% confidence interval: 0.18-0.76; P=0.007), but not OS. CONCLUSIONS: Our findings suggest that PD-L1 expression levels in tumor cells may influence postoperative prognosis and relapse risk in patients with PM undergoing P/D. Lower PD-L1 expression correlates with improved survival outcomes, positioning PD-L1 as a potential biomarker to inform therapeutic strategies in this population. Further studies are warranted to explore the implications of PD-L1 in treatment decisions.