Prognostic value of PD-L1 expression in patients with pancreatic cancer A PRISMA-compliant meta-analysis

Background: Programmed cell death ligand 1 (PD-L1) expression was reported to be associated with poor prognosis in various solid tumors. However, the prognosis value of PD-L1 in pancreatic cancer remained inconclusive. We performed a meta-analysis to assess the clinical value of PD-L1 as a novel prognostic biomarker of pancreatic cancer. Methods: PubMed, Embase, and Web of Science were searched up to October 2018. The HRs and 95% CIs for overall survival (OS) and cancer-specific survival (CSS) according to the expressional status of PD-L1 were pooled. The combined odd ratios (ORs) and 95% CIs were utilized to assess the association between PD-L1 and clinicopathological characteristics. Results: A total of 9 studies with 993 patients were included. Elevated PD-L1 expression was related with poor OS (HR = 1.63, 95% CI = 1.34-1.98, P < .001) and CSS (HR = 1.86, 95% CI = 1.34-2.57, P <. 001). Furthermore, high PD-L1 expression was also demonstrated to be associated with positive N stage (OR = 1.81, 95% CI = 1.21-2.71, P = .004), advanced T stage (OR = 1.86, 95% CI = 1.08-3.19, P = .025), and low differentiation (OR = 2.24, 95% CI = 1.16-4.33, P = .017). However, PD-L1 has nonsignificant correlation with M stage, gender, or age. Conclusion: This study suggests that PD-L1 is a potential prognostic biomarker and may be helpful to clinicians aiming to select the appropriate immunotherapy for pancreatic cancer.