Proton Versus Photon Therapy in Anal Squamous Cell Carcinoma

Inclusion Criteria:

1. The patient must be at least 18 years old

2. Histologically confirmed, previously untreated squamous cell carcinoma (p16-positiveor p16-negative) of the anal canal (ICD-O-3 C21), i.e. cancer of the perianal skinwithout connection to the anal canal are not included. The patients may have primarytumour, regional nodes, metastasis (TNM)-stage T2 (>4 cm) -4,N0-1c,M0 (UICC 8thedition).

3. World Health Organisation/Eastern Cooperative Oncology Group (WHO/ECOG) performancestatus 0-1

4. The patient must be able to understand the information about the treatment and givea written informed consent.

Exclusion Criteria:

1. Patients with cancer of the perianal skin without involvement of the anal canal (ICD-O-3 C44.5) are not eligible.

2. Patient judged to have any other treatment than radiotherapy with concomitantchemotherapy as the preferred treatment

3. Concomitant or previous malignancies. Exceptions are, adequately treated basal cellcarcinoma or squamous cell carcinoma of the skin or, other previous malignancy witha disease-free interval of at least 5 years.

4. Two or more synchronous primary cancers in the pelvic region at time of diagnosis

5. Previous radiotherapy, surgery or chemotherapy that may interfere with the plannedtreatment for the present disease, as judged by the investigator.

6. Co-existing disease prejudicing survival (expected survival should be >2 years).

7. Pregnancy or breast feeding

8. When prosthetic materials (e.g. hip prostheses) are present close to the targetvolume it must be considered if this may introduce uncertainties in dosecalculations that precludes especially, proton therapy.

9. Patients with pacemaker/ICD are not eligible.