The clinicopathological and prognostic value of PD-L1 in urothelial carcinoma: a meta-analysis

The prognostic value of programed death-ligand 1 (PD-L1) in urothelial carcinoma (UC) has been assessed in previous studies, while the results remain controversial and heterogeneous. Therefore, we performed this meta-analysis to explore the prognostic effect of PD-L1 in patients with UC. PubMed, Embase and Web of Science were searched to identify the studies. Hazard ratios (HR) with 95% confidence interval (95% CI) and clinicopathological factors were extracted from included studies. A total of 1819 patients with UC from 11 published studies were incorporated. The results of meta-analysis showed that positive PD-L1 expression was significantly associated with poorer overall survival (OS) (HR 1.59, 95% CI 1.05-2.40) and disease-free survival (DFS) (HR 1.83, 95% CI 1.03-3.25), but not recurrence-free survival. Moreover, in the subgroup analysis, significant associations between PD-L1 expression and OS or DFS were found in bladder UC, the cutoff value of positive expression of PD-L1 >= 5% and the expression of PD-L1 on the tumor cell membrane. Interestingly, positive PD-L1 expression was correlated with poorer pathological T stage (OR 2.03, 95% CI 1.46-2.82). Our meta-analysis implies that PD-L1 might be a valuable biomarker of poor prognosis for UC, especially bladder UC, although further large-scale and well-designed studies are warranted to verify the prognostic value of PD-L1 for UC.