Adaptative Radiotherapy to Decrease Xerostomia in Oropharynx Carcinoma (ARTOME)

Inclusion Criteria: * Locally advanced non-metastatic carcinoma of the oropharynx limited to T3 and T4 (whatever the N) and N2-N3 (whatever the T)(AJCC stage III-IV) * Age ≥ 18 years and ≤ 75 years * Performance status (WHO ≤ 2) * Renal, hepatic and cardiovascular functions allowing systemic treatment administration * Adapted stomatologic care * Signed informed consent form * Membership or beneficiary of a national insurance scheme Exclusion Criteria: * Both parotids totally included in the target volume * Stages T1 or T2 with positive node disease N1 * Neoadjuvant chemotherapy * Exereses of primitive tumor and/or nodes * History of other cancer within 5 years (except for basocellular epithelioma and cervical) * Previous neck radiotherapy * Platinum salts, 5FluoroUracile (5FU) agents or cetuximab chemotherapy * Unstable diseases (cardiovascular, renal, pulmonary, systemic lupus or sclerodermia) incompatible with study participation * Patient participating in other therapeutic trial with experimental drug, 30 days before the inclusion. * Patient already recruited in another biomedical research ( non interventional study is authorized) * Pregnant or breast feeding patients * Patient deprived of liberty, under tutorship, guardianship or placed under judicial protection * Patient is deemed incapable of giving informed consent * Patients who, for family, social, geographic or psychological reasons, cannot be adequately followed up and/or are incapable of undergoing regular controls.