CD8A and neoplasm: The relationship between various clinicopathological factors and serum/tumors PD-L1 levels showed that smokers (p = 0.024), an advanced stage (p = 0.025), non-adenocarcinoma (p = 0.001), EGFR wild-type tumors (p = 0.029), vascular invasion (p < 0.001), lymph node metastasis (p = 0.001), elevated serum PD-L1 level (p < 0.001), and an increased number of CD8+ TILs (p = 0.007) were significantly associated with patients with tumor PD-L1 ≥ 1% (Table 2).