CDKN2A and head and neck squamous cell carcinoma: It is widely known that tobacco-associated HPV-HNSCC has a high mutational load and is characterized by multiple molecular alterations, such as deleterious mutations of or loss of p53 (84%), mutation or loss of CDKN2A (58%), amplification of CCND1 (31%), which is an oncogene implicated in cell cycle regulation, amplification of MYC (14%) and overactivation of PI3K kinase pathway (30%) [15,16].