DKK1 and head and neck squamous cell carcinoma: A poor HNSCC prognosis was linked to DKK1 upregulation in grade 1 (OS: HR = 3.81, P = 0.0049), grade 2 (OS: HR = 2.02, P = 6.8e−05; RFS: HR = 3.36, P = 0.019), grade 3 (OS: HR = 2.69, P = 0.00027), stage 2 (OS: HR = 2.94, P = 0.0097), stage 3 (OS: HR = 5.52, p = 0.00022), stage 4 (OS: HR = 1.73, P = 0.0026), and both males (OS: HR = 2.3, P = 2.1e−06), and females (OS: hazard ratio [HR] = 2.49, P = 0.0033).