CD274 and metastatic malignant neoplasm in the lymph nodes: No significant correlations were found between PD-L1 expression and patient age (P=0.819), sex (P=0.082), smoking (P=0.396), drinking (P=0.171), tumor size (P=0.927), tumor site (P=0.682), differentiation (P=0.941), vessel and nerve invasion (P=0.365 and 0.071), lymph node metastasis (P=0.403), and pTNM stages (P=0.716).