CD274 and anemia: Factors significantly correlated with OS by univariate analyses were age at recurrence (P = 0.043, Figure 5B), the level of PD-L1 staining (P = 0.001, Figure 5A), T-stage of recurrence (P ≤ 0.001, Figure 5C), pre-retreatment anemia (P = 0.007, Figure 5D) and tumor necrosis (P = 0.026, Figure 5E).