Overview

The standard practice in management of carcinoma of anal canal is to treat patients with radiotherapy using the IMRT technique along with chemotherapy. It is known that while IMRT has reduced treatment related side effects as compared to the older radiation techniques, reducing these side effects further still remains a major challenge.

These side-effects include gastrointestinal (diarrhea, altered bowel habits, weight loss, bleeding, obstruction), genitourinary (difficulties in passing urine, passing blood in urine, difficulty in holding urine) and hematologic toxicities (anemia, low platelet count and increased predisposition to infections).

Proton therapy (IMPT) is a form of radiation treatment in which high doses can be delivered within the tumor while the surrounding normal tissues receive a lesser radiation dose. It is believed that these physical properties of proton therapy may help reduce the side effects of treatment.

Patients will be randomly assigned to either receive IMRT or IMPT based treatment so as to see whether it is possible to reduce the acute treatment related toxicities. In this study, there is a 66.7% chance that the patient will get IMPT based treatment, which may be able to reduce the toxicities.

Eligibility

Inclusion Criteria:

1. Age > 18 and < 80 years of age
2. Histologically confirmed squamous cell carcinoma of the anal canal or distal rectum
3. The patients may have TNM stage T1-2 N+M0 or T3-4 N0-1c M0 (UICC 8th edition)
4. Involvement of lower para-aortic lymph nodes (till renal hilum) as the only site of disease extension on PET CECT may also be included as they receive radical chemoradiation as standard treatment.
5. WHO or ECOG performance status 0-1
6. HIV testing is known and HPV (P16) testing done on tissue sample.
7. With suitable blood test values for standard concurrent chemotherapy (Hb > 10 mg/dL, ANC > 1.5 cells/mm3, Platelets > 100,000 cells/mm3, Creatinine < 1.5 x ULN, Bilirubin < 3 x ULN, ALT < 3 x ULN) as deemed by a medical oncologist in team.
8. The patient must be expected to tolerate the treatment and be compliant for follow up.
9. No contradiction for chemoradiation such as inflammatory bowel disease, pregnancy, etc.
10. Willing to consent to participate in the study.

Exclusion Criteria:

1. Two or more synchronous primary cancers.
2. 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, which may affect the treatment planning process.
3. Ulcerative colitis or any other histologically confirmed inflammatory bowel disease.
4. Poor reliability for follow-up and treatment completion.