The univariate Cox regression model showed that tumour differentiation, lymph node metastasis, TNM stage, PD-L1 expression and the SUVmax were correlated with OS, whereas age, gender, smoking history, tumour size, serum CEA levels, serum SCC levels, and serum CYFRA21-1 levels were not significantly correlated with OS. This evidence concerns the gene CD274 and metastatic malignant neoplasm in the lymph nodes.