Concomitant radiotherapy and chemotherapy for anal cancer.

Concomitant radiotherapy/chemotherapy is widely used to treat epidermoid cancers of the anal canal. The drugs most frequently combined with radiotherapy are 5-fluorouracil and mitomycin, but other schedules include 5-fluorouracil and cisplatin, 5-fluorouracil alone, or bleomycin alone. Since mechanisms of possible interaction between radiotherapy and the cytotoxic drugs are not well understood, schedules have been developed empirically. Randomized trials comparing radiotherapy/chemotherapy with radical radiotherapy alone have not yet been completed. In nonrandomized studies, however, some drug and radiotherapy combinations appear to be superior to radiotherapy alone. Combined modality therapy has resulted in 5-year survival rates of 65% to 80%; approximately 85% of patients retain anorectal function when the primary tumor is controlled by concomitant radiotherapy/chemotherapy.