This study is being conducted to evaluate the efficacy of palifermin administered intravenously (IV) in weekly doses (minimum of 7 weekly doses, until RT was complete) in reducing the incidence of severe (World Health Organization [WHO] grade 3 or 4) oral mucositis in subjects with locally advanced HNC receiving RT concurrent with CT (RT/CT) as adjuvant treatment for their disease (postoperative setting). This study will assess the safety and tolerability of palifermin at the dose of 120 μg/kg IV administered weekly (minimum 7 weekly doses, until RT was complete) in this subject population. This study will also evaluate the effect of palifermin on the clinical sequelae of severe OM (eg, average subject-reported mouth and throat soreness [MTS] score), and on RT-induced xerostomia in this population, as well as the long-term effects of palifermin on disease outcome and survival in this population.