CTLA4 and head and neck squamous cell carcinoma: Subsequently, the correlation between the risk score and the expression of five immune checkpoint genes, CTLA4, LAG3, PD1, PD-L1, and TIM3, indicated that the expression of immune checkpoint genes was negatively correlated with the risk score and was highly expressed in the low-risk group, suggesting that immune checkpoint inhibitors may be beneficial to patients with HNSCC with low risk scores.