CD274 and neoplasm: In 14 eligible studies, the PD-L1 expression statuses were evaluated by the percentage of tumor cells that were PD-L1-expression-positive, which varied from 27% to 89%, while the pooled estimated expression level of PD-L1 in TETs was 71% (95% CI, [0.59; 0.81], p < 0.01, random effect model) (Figure 10).