DAPK1 and head and neck squamous cell carcinoma: The significant association between DAPK promoter methylation and HNSCC was displayed among the MSP in the random-effect model and the QMSP in the fixed-effect model (MSP, OR = 2.97, 95% CI = 1.55–5.70; QMSP, OR = 8.84, 95% CI = 5.22–14.99).