The purpose of this study is to determine the 1-year rate of locoregional disease control in the experimental arm, using a control arm to avoid selection bias.

• To determine the 1-year rate of locoregional disease control in the experimental arm, using a control arm to avoid selection bias.
• To determine the 2 and 3 year rate of locoregional disease control.
• To evaluate the safety and toxicity of the combination of cetuximab and concomitant-boost accelerated radiotherapy followed by 12 weeks of complementary treatment with cetuximab. Both acute and chronic toxicity will be assessed.
• To determine specific disease-free survival, event-free survival, disease-specific survival and overall survival
• To determine acute and late toxicity
• To determine EGFR, p53, Ki67, and evaluate its value as a prognostic factor.

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.