We have analyzed the development of resistance to small-molecule EGFR inhibitors gefitinib and erlotinib, which are used in non-small-cell lung cancers with mutated EGFR and that have been tested in other EGFR-driven tumors including breast cancers [38,39,40,41] and cetuximab, an anti-EGFR monoclonal antibody used for the treatment of colorectal cancer (with wild-type KRAS), non-small cell lung cancer and head and neck cancer [42]. This evidence concerns the gene EGFR and head and neck cancer.