Adaptive Radiation in Anal Cancer

Subjects will receive 54 Gy of radiation delivered 5 day a week for 6 weeks, 30 radiation treatments total. Intensity-Modulated photon radiation therapy will be delivered on a Varian Ethos linear accelerator. Daily image-guided radiation therapy (IGRT) is required. All treatments will have artificial-intelligence (AI) daily adaptations of the radiation plan to optimize the radiation dose to the targeted area and minimize radiation dose to the normal surrounding organs such as the bowel.

As part of the subjects' treatment, 10 mg/meters squared of Mitomycin C will be administered intravenously (IV-into the vein) on Day 1 and Day 29.

As part of the subjects' treatment, 1g/meters squared/day for 4 days of 5-Fluorouracil will be administered by continuous infusion on Days 1-4 (for 96 hours) and Days 29-32 (for 96 hours). 5-Fluorouracil or capecitabine will be administered per the physician's discretion.

As part of the subjects' treatment, 825 mg/meters squared per day, divided into 2 daily doses, will be taken on days of radiotherapy. Capecitabine or 5-FU will be administered per the physician's discretion.