EGFR and head and neck squamous cell carcinoma: EGFR overexpression is an early event in SCCHN carcinogenesis; it is already present in "healthy" mucosa (field cancerization) from cancer patients, when compared to healthy controls; this overexpression will increase steadily in parallel to observed histological abnormalities, from hyperplasia to invasive carcinoma, through dysplasia and in situ carcinoma [16].