Feasibility and Safety of CareMin650 in Patients at Risk of or Suffering From Oral Mucositis and/or Radiation Dermatitis

Inclusion Criteria: Inclusion Criteria common to both cohorts: * Adult patients (age ≥18 years) accepting to participate in the study and having signed the written informed consent form prior to any protocol-specific procedures. * Having an ECOG (Eastern Cooperative Oncology Group) performance status ≤ 2. * Having a life expectancy greater than 3 months according to the investigator medical judgement. * Having the ability to understand and sign the written informed consent form and willing to comply with protocol requirements. Specific criteria for inclusion in head and neck cancer cohort (cohort A): * Patient with histologically proven squamous cell carcinoma of oropharynx, nasopharynx, hypopharynx, larynx or oral cavity with or without prior surgical resection * Patient with dental examination prior to chemo-radiotherapy and any required dental treatment performed * In cohort A1 (patient with no oral mucosa or skin lesion, starting radiotherapy), patient scheduled to receive intensity modulated radiation therapy on at least 50% of the oral mucosa at a total dose of at least 40 Gy, alone or associated with chemotherapy or targeted therapies. * In cohort A2, (on-going radiotherapy), presence of oral mucositis and/or radiation dermatitis grade 1, 2 or 3. Specific criteria for inclusion in breast cancer cohort (cohort B) * Patient with histologically proven breast cancer * After breast-conserving surgery, or total mastectomy if the patient is at high risk of radiodermatitis based on the investigator's judgement. * In cohort B1, (patient with no skin lesion starting radiotherapy) patient scheduled to receive radiation therapy. * In cohort B2 (on-going radiotherapy) presence of radiation dermatitis grade 1, 2 or 3. Exclusion Criteria: Exclusion Criteria common to both cohorts: * Any condition that may interfere with adherence to treatment according to the investigator's judgment * Patient under guardianship or deprived of his liberty by a judicial or administrative decision or incapable of giving its consent. * Patient with a known polyurethane allergy * Females patients who are pregnant or breastfeeding * Female patients who do not fall into 1 of the following categories: * Post-menopausal * Surgically sterile * Using one of the following birth control methods throughout the duration of the study: * Intrauterine device (\> 14 days) * Barrier method (condom or diaphragm) with spermicide (\> 14 days) * Hormonal contraception (same dose and same formulation for at least 6 months) * Patient participating in another clinical trial involving drugs or non-drug therapies aiming to treat or prevent lesions induced by radiotherapy Specific criteria for non inclusion in head and neck cancer cohort (coh ort A): * Active bleeding, coagulopathy or pathologic condition that would confer a high risk of bleeding * Hb \< 8g/dL; neutrophils \< 1000 mm3; platelets \< 50 000/mm3 Specific criteria for non inclusion in breast cancer cohort (cohort B): * Previous irradiation to the same breast * Any pre-existing skin disorders located on the chest