Cetuximab & Concomitant-Boost Accelerated RT in Patients With Locally Advanced Oropharynx Squamous Cell Carcinoma.

Inclusion Criteria: * Written informed consent. * Aged between 18 and 80, inclusive. * Karnofsky functional status \>= 70% at the time of enrolment in study. * Life expectancy of more than 3 months. * Histologically confirmed diagnosis of oropharyngeal squamous cell carcinoma: base of tongue, vallecula, tonsil and tonsillar fossa and pillars, glossotonsillar sulcus, inferior surface of the soft palate, uvula and lateral and posterior oropharyngeal wall. * Stage III or IV with no evidence of distant metastasis (IVA or IV B) * Patients in medical conditions to receive a radical concomitant-boost accelerated radiotherapy treatment. * Neutrophils \>= 1500/ mm3, platelet count \>= 100 000/ mm3 and haemoglobin \>= 10 g/ dL. * Proper liver function: total bilirubin \<= 1.5 x upper limit of normal (ULN); aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \<= 2.5 x ULN. * Proper renal function: serum creatinine \<= 1.5 x ULN; if the values are \> 1.5 x ULN, creatinine clearance should be \>= 55 ml/min. * Serum calcium within normal limits. * Adequate nutritional state: weight loss \< 20% with respect to usual weight and serum albumin \> 35 g/l. * Effective birth control method if there is possibility of conception and/or pregnancy. * Availability of tumour tissue for immunohistochemical analysis of EGFR expression. Exclusion Criteria: * Metastatic disease. * Previous surgical, radiotherapy and/or chemotherapy treatment for the disease in the study. * Other non-oropharyngeal tumour sites in the head and neck area. * Other previous and/or simultaneous squamous cell carcinoma. * Diagnosis of any other cancer in the previous 5 years, except properly treated carcinoma in situ of the uterine cervix and/or basal cell skin carcinoma. * Active infection (infection requiring intravenous antibiotics), including active tuberculosis and diagnosed HIV. * Uncontrolled hypertension defined as systolic blood pressure \>= 180 mm Hg and/or diastolic blood pressure \>= 130 mm Hg at rest. * Pregnancy (absence of pregnancy must be confirmed with the serum-HCG test) or breast-feeding women. * Chronic, concomitant systemic immunotherapy, or hormonal treatment for the cancer. * Other concomitant anti-cancer treatments. * Clinically significant coronary artery disease, history of myocardial infarction in the previous 12 months or high risk of out of control arrhythmia or cardiac insufficiency. * Chronic obstructive pulmonary disease which may have required \> 3 hospitalisations in the previous 12 months. * Out of control active peptic ulcer. * Presence of a psychological or medical illness which might impede the patient from carrying out the study or giving his or her signature on the informed consent * Known drug abuse (with the exception of excessive alcohol consumption) * Known allergic reaction to any of the components of the treatment to be studied. * Previous treatment with monoclonal antibodies or signal transduction inhibitors or other EGFR-targeted treatment. * Any experimental treatment in the 30 days prior to enrolment in the study.