EGFR and head and neck squamous cell carcinoma: Except for an efficient immune response to foreign virus, especially a high level of CD8+ T cells in the tumor microenvironment, there are some other reasons contributing to the better prognosis and astonishing sensitivity to radiotherapy and chemotherapy of HPV-positive HNSCC, including lower expression of epidermal growth factor receptor (EGFR), overexpression of p16, a decreased p53 mutation rate and lower hypoxia (109, 110).