<qa>  What is the epidermal growth factor receptor?The epidermal growth factor receptor EGFR, a member of the ErbB family of receptor tyrosine kinases, is abnormally activated in nearly all epithelial cancers, including HNC. Nearly all HNC expressing high levels of EGFR have been associated with poor outcomes. Radiation therapy can lead to increased expression of EGFR in cancer cells, and blockade of EGFR signaling has been shown to sensitize cells to ionizing radiation. The use of monoclonal antibodies directed against EGFR has a rich pre-clinical record. However, it was not until the publication of the Bonner trial that combined radiotherapy plus anti-EGFR therapy was shown to be successful in the clinic to treat HNSCC. This study showed that the addition of single agent cetuximab 250 mgm2 given weekly with concurrent radiation therapy improved median overall survival from 29 to 49 months. Furthermore, progression-free survival was improved from 12 to 17.1 months. In addition, patients were able to tolerate the regimen with no difference in rates of mucositis. Other toxicities were also similar to radiotherapy alone, with the exceptions of a small risk of infusion reactions, and the common - but non-dose limiting - occurrence of an acneiform rash. 