Inclusion Criteria:

• Patient aged 18 years or older
• Performance Status 0-2
• Patient with oral cavity cancer (soft tissue or soft tissue-bone flap), treated by reconstructive surgery with a flap. Oropharynx cancer whose flap extends significantly into the oral cavity may be included in the study
• Quality of resection with margins > 1 mm
• Patient candidate to post-operative radiotherapy (Intensity-Modulated Radiation Therapy (IMRT) or proton therapy)
• Concomitant chemotherapy is allowed (stratification parameter)
• Patient must have signed a written informed consent form prior to any trial specific procedures
• Patient affiliated to the social security system

Exclusion Criteria:

• Local flap (small size limiting IMRT modulation potential)
• History of radiotherapy of head and neck area
• Metastatic disease
• History of other malignancy within the previous 3 years (except for appropriately treated in-situ cervix carcinoma and non-melanoma skin carcinoma)
• Simultaneous participation in another clinical study may compromise the conduct of this study.
• Pregnant or lactating women
• Patient assessed by the investigator to be unable or unwilling to comply with the requirements of the protocol
• Patient deprived of freedom or under guardianship