CDKN2A and head and neck squamous cell carcinoma: The frequency of patients with HNSCC, independent of the primary site, who died after surgery, chemotherapy, radiotherapy and concomitant chemotherapy and radiotherapy with positive expression of the p16INK4a protein were, respectively, 23.5, 47.8, 25.0 and 21.2%, while with negative expression of the p16INK4a protein were, respectively, 18.2, 30.9, 68.3 and 20.8%, regardless of survival time and primary anatomic site.