Photon Therapy Versus Proton Therapy in Early Tonsil Cancer.

Inclusion Criteria:

1. The patient must be at least 18 years old.
2. Histologically or cytologically confirmed, previously untreated squamous cell carcinoma of the tonsil T1-2 (p16-positive or p16-negative) N0-1 M0 (p16-positive)/N0-N2b M0 (p16-negative) according to AJCC 8th edition, aimed for unimodal and ipsilateral treatment with radiotherapy with curative intent. The treatment may be followed but not preceded by surgery, which would be as a salvage procedure and not part of the planned treatment. An excision of a lymph node, or a tonsillectomy for diagnostic purposes does not exclude the patient from participation.
3. World Health Organisation/Eastern Cooperative Oncology Group (WHO/ECOG) performance status 0-1.
4. The patient must be able to understand the information about the treatment and give a written informed consent.

Exclusion Criteria:

1. Patients judged to benefit from bilateral radiotherapy or concomitant chemotherapy
2. Concomitant or previous malignancies. Exceptions are adequately treated basal cell carcinoma or squamous cell carcinoma of the skin, or in situ carcinoma of the cervix uteri with a follow-up time of at least 3 years, or other previous malignancy with a disease-free interval of at least 5 years.
3. Two or more synchronous primary cancers in the head and neck region at time of diagnosis
4. Previous surgery or radiotherapy in the head and neck region that may affect the study result, as judged by the investigator
5. Co-existing disease prejudicing survival (expected survival should be \>2 years).
6. Psychiatric or addictive disorders or other medical conditions which in the view of the investigator might impair patient compliance
7. When dental fillings with amalgam or metal are present close to the tumour area it must be considered if this may affect radiotherapy before inclusion.