CDKN2A and head and neck squamous cell carcinoma: The frequence of patients with HNSCC, independent of the primary site, who died after the diagnosis of the disease with positive expression of the p16INK4a protein with clinical stage I, II, III, and IV were, respectively, 31.6, 40.0, 30.0 and 36.7%, while with negative expression of the p16INK4a protein were, respectively, 12.0, 16.7, 27.6 and 29.8%, regardless of survival time and primary anatomic site.