Patients with oral cavity cancer treated by reconstructive surgery with a flap.

Patients will be treated in the study for :

• Experimental arm: Post-operative radiotherapy with flap sparing
• Control arm: Standard post-operative radiotherapy without flap sparing (current practice) Radiotherapy by IMRT using photons or proton therapy (IMPT)

Patients with oral cavity cancer treated by reconstructive surgery with a flap.

Patients will be treated in the study for :

• Experimental arm: Post-operative radiotherapy with flap sparing
• Control arm: Standard post-operative radiotherapy without flap sparing (current practice) Radiotherapy by IMRT using photons or proton therapy (IMPT) Our purpose is to demonstrate the feasibility of sparing surgical flaps from radiotherapy, in order to reduce toxicity while maintaining local disease control.

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