Specifically, hypermethylation of EDNRB in ctDNA was found to be significantly associated with HNSCC when comparing a pooled group of HPV-positive and HPV-negative HNSCC patients to healthy controls; however, hypermethylation of EDNRB was only detectable in a minority of HNSCC patients, limiting its value as a diagnostic biomarker [26]. This evidence concerns the gene EDNRB and head and neck squamous cell carcinoma.