Proton Versus Photon Therapy in Anal Squamous Cell Carcinoma

Dosimetric studies suggest that radiotherapy with protons has a potential to reduce side effects compared to treatment with photons for patients with anal carcinoma (AC). There are so far no studies comparing these treatment techniques in a randomised setting. The aim of this study is to compare side effects following photon therapy versus proton therapy within the framework of a randomised controlled trial.

Anal carcinoma is a disease in which modern therapy is reasonably successful in achieving tumour control/cure. Both acute and late side effects are substantial. Proton radiotherapy is hypothesised to have the potential to decrease the incidence/severity of some acute side effects from certain organs at risk e.g. bone marrow and intraperitoneal bowel. By sparing the dose to these organs it is also possible that late effects might be less evident. Sparing of the bone marrow may lead to fewer septic events and dose reductions of chemotherapy which may, as a consequence, improve tumour control. The primary aim of this study is to find ways to decrease acute side effects primarily to alleviate some discomfort from the patient during and after a usually painful treatment experience. It has also been concluded by others that reduction of acute side effects is a relevant aim and end point for the evaluation of new treatment techniques and both patient reported and physician reported data are assessed

Eligibility Criteria:
Inclusion Criteria:

1. The patient must be at least 18 years old
2. Histologically confirmed, previously untreated squamous cell carcinoma (p16-positive or p16-negative) of the anal canal (ICD-O-3 C21), i.e. cancer of the perianal skin without connection to the anal canal are not included. The patients may have primary tumour, regional nodes, metastasis (TNM)-stage T2 (\>4 cm) -4,N0-1c,M0 (UICC 8th edition).
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 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 concomitant chemotherapy as the preferred treatment
3. Concomitant or previous malignancies. Exceptions are, adequately treated basal cell carcinoma or squamous cell carcinoma of the skin or, other previous malignancy with a 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 planned treatment 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 target volume it must be considered if this may introduce uncertainties in dose calculations that precludes especially, proton therapy.
9. Patients with pacemaker/ICD are not eligible.