CDKN2A and head and neck squamous cell carcinoma: When considering methylation patterns in ctDNA of salivary samples, Lim et al. found that genes RASSF1α, CDKN2A, TIMP3, and PCQAP/MED15 had higher levels of methylation in HPV-negative HNSCC patients compared to healthy controls, while the same genes had lower levels of methylation in HPV-positive HNSCC patients compared to healthy controls [27].