The hypothesis is that helical tomotherapy could minimize radiation related toxicity by avoiding or limiting doses to structures such as small bowel, external genitalia, skin, bladder, rectum, and femoral neck and head.

This is a phase II study using tomotherapy for radiation treatment delivery along with concurrent 5-FU/mitomycin C for the treatment of T2-T4 cancer of the anal canal. They hypothesis is that helical tomotherapy could minimize radiation related toxicity by avoiding or limiting doses to structures such as small bowel, external genitalia, skin, bladder, rectum, and femoral neck and head. This is expected to limit or reduce treatment related toxicity and hence prevent or reduce treatment breaks. This may result in delivery of radical treatment with better local control and treatment outcome than using the current radiation treatment technique at our center.

Inclusion Criteria:

• Patient should have histologically proven primary squamous carcinoma or its variant
• No history of prior malignancy.
• Patients must be free of metastatic disease out of pelvis at the time of diagnosis
• Patients must be at least 18 years of age
• Performance status 0, 1 or 2 ECOG
• T stage 2-4, Any N, stage MO
• Patient should be eligible for concomitant chemotherapy
• Informed written consent required to participate

Exclusion Criteria:

• Prior radiation to pelvis
• Pregnant or lactating
• prior surgical treatment for anal cancer other than biopsy
• prior surgical or chemotherapy treatment for anal cancer
• T1 tumours (2cm) or evidence of distant mets
• comorbid medical conditions precluding radical treatment at the discretion of oncologist