DAPK1 and head and neck squamous cell carcinoma: The detection of the tumor with an overall accuracy of 81% in DNA isolated from the saliva of patients with HNSCC compared to DNA isolated from the saliva of healthy non-smoking individuals (p < 0.0001)Promoter methylation of the RASSF1A, DAPK1, and p16 MSP panel may be a potentially useful method in detecting of the early stages of HNSCC