Clinicopathological and prognostic significance of PD-L1 expression in oral squamous cell carcinoma: a meta analysis

Objective: To determine the prognostic role of high PD-L1 in patients with oral squamous cell carcinoma.

Methods: Electronic databases, such as PubMed, Embase and Cochrane library, were searched to identify studies evaluating PD-L1 expression and overall survival (OS) in these patients. RevMan 5.3 software was used for meta-analysis.

Results: A total of 12 studies that involved 1595 patients were included. Pooled hazard ratio (HR) 1.02 (95%CI= 0.93-1.11,P=0.71) indicated that the association between PD-L1 expression and overall survival (OS) was not significant. The pooled odds ratios (ORs) indicated that PD-L1 expression was associated with gender (OR=0.64, 95%CI=0.48-0.85, P=0.002), differentiation (OR=0.58, 95%CI=0.37-0.90, P=0.01) and HPV infection (OR=1.91, 95%CI=1.13-3.23, P=0.02). However, PD-L1 had no correlation with tumour size, and lymph node status.

Conclusions: PD-L1 expression may not be an independent predictor of prognosis of patients with OSCC. Well-designed large cohort studies are needed to confirm these findings.