NFE2L2 and head and neck squamous cell carcinoma: Nrf2 is overexpressed in several types of human cancer, including cancer of the lung, breast, oesophagus, ovary, prostate, pancreatic, colorectal, head and neck squamous cell carcinoma, gallbladder and skin which indicates that the cytoprotective properties of the Nrf2 pathway can be exploited by tumor cells to promote their survival [60, 61].