Prognostic And Clinicopathological Significance Of PD-L1 Expression For Colorectal Cancer:A Meta-analysis

Objective:To systematically evaluated the prognostic and clinicopathological significance of PD-L1 expression in tumor tissues in colorectal cancer(CRC)by meta-analysis.Methods: Articles were included from PubMed,Embase,Web of Science and Cochrane Library.Survival data and clinicopathological parameters were extracted from individual studies and analyzed by Stata SE12.0 software.Results: Eighteen studies totaling with 5,724 CRC patients are enrolled.PD-L1 expression in tumor tissues was significantly associated with shorter OS(HR:1.40,95%CI:1.02-1.93,P=0.039)and RFS(HR:1.67,95%CI:1.27-2.20,P=0.000),but not with DFS(P=0.933)in CRC.And pooled ORs showed that PD-L1 expression was significantly associated with tumor differentiation(OR:1.56,95%CI:1.09-2.22,P=0.016)and lymph node metastasis(OR:0.82,95%CI:0.69-0.98,P=0.028),but not with gender,tumor location,TNM staging,invasion depth,venous invasion,chemotherapy,MSI status and KRAS mutation.In addition,subgroup analysis showed that PD-L1 expression on tumor cells,not on tumor infiltrating immune cells(OS P=0.991;RFS P=0.210),was significantly associated with shorter OS(HR:1.40,95%CI:1.03-1.90,P=0.033)and RFS(HR:2.46,95%CI:1.44-4.20,P=0.001).Conclusions: PD-L1 expression in tumor tissues is associated with shorter survival in CRC.In addition,the prognostic significance of PD-L1 expression on tumor cells might be inconsistent with that on tumor infiltrating immune cells.