This randomised, double-blind study will compare an oral immunomodulatory solution to a placebo for the prevention of acute severe mucositis in head and neck cancer patients treated surgically and concomitantly with radiochemotherapy. The investigators expect a decrease of 25% of severe acute mucositis in experimental arm.

Inclusion Criteria:

• Epidermal carcinoma proven histologically of the sphere ORL (all locations except nasopharynx).
• Patients with tumours of the oral cavity, the oropharynx, the hypopharynx and the larynx treated initially by surgery and eligible for post-operative radio- chemotherapy concomitantly.

NB. The patients with tumours of the larynx or hypopharynx are eligible if the radiotherapy to the oropharyngeal mucosa will be at least 54 Gy and the mucositis can be visualised without the use of instruments.

• Radio-chemotherapy to be given postoperatively.
• Maximum delay of 8 weeks between the operative date and the planned starting date of radio-chemotherapy.
• Performance status (grade OMS): 0, 1, 2
• Nutritional Risk Index ≥ 83.5
• No mucositis.
• Age: 18-75 years
• Life expectancy ≥ 3 months.
• Informed consent obtained from the patient.
• Affiliation with a social security system.

Exclusion Criteria:

• Tumour of nasopharynx
• Mucositis
• Severe sepsis
• Treatment by immunomodulators in the month preceding inclusion
• ATCD allergy to the components of Oral Impact.
• Parenteral nutrition at inclusion
• Usual contraindications to concomitant radio-chemotherapy
• Patient already included in another therapeutic trial involving an experimental molecule
• Female pregnant or susceptible to being pregnant, or breast-feeding. Patient not using appropriate contraceptive measures during the treatment
• Persons deprived of liberty or under guardianship
• Patients unable to commit to the trial schedule for geographical, social or psychological reasons.