CDKN2A and head and neck squamous cell carcinoma: In the present study, the detection frequency of P16INK4A promoter methylation was 44.2%, while other studies using saliva as a source of genomic DNA show detection rates of 47.8% (17) and 17.2% (21) in OSCC, and of 47.0% (24), 29.0% (15), and 25.0% (8), in HNSCC.