CD274 and metastatic malignant neoplasm in the lymph nodes: Expression of both analyzed PD-L1 variants (PD-L1_4 and PD-L1_2) in whole blood samples of OSCC patients was significantly higher in cases with lymph node metastases (N+) compared to cases without lymph node metastases (N0) (mean PD-L1_4 ΔCT N+ 6.29, mean PD-L1_4 ΔCT N0 7.35; p = 0.002; mean PD-L1_2 ΔCT N+ 6.30, mean PD-L1_2 ΔCT N0 7.37; p = 0.003) (Table 4, Figure 2A, 2B).