Chemotherapy Plus Radiation Therapy in Treating Patients With Stage II or Stage III Anal Cancer

OBJECTIVES: * Compare the initial and total local and distant failure rates in patients with anal canal cancer treated with either fluorouracil (5-FU) plus mitomycin concurrently with radiotherapy or 5-FU plus cisplatin followed by 5-FU plus cisplatin concurrently with radiotherapy. * Identify any differences in local control and colostomy rates at 2 years in patients treated with these regimens. * Determine any difference in colostomy free, disease free, or overall survival in patients treated with these regimens. * Compare the toxic effects of these regimens in these patients. * Evaluate the prognostic effects of tumor markers P53 overexpression, human papilloma virus status, and enzyme HAP1 in patients treated with these regimens. OUTLINE: This is a randomized study. Patients are stratified according to gender, nodal status (positive vs negative), and primary tumor size (greater than 2 cm to 5 cm vs greater than 5 cm). Patients are randomized to 1 of 2 treatment arms. * Arm I: Patients receive fluorouracil (5-FU) IV continuously over 96 hours beginning on days 1 and 29 and mitomycin IV on days 1 and 29 with concurrent radiotherapy. * Arm II: Patients receive induction chemotherapy comprising 5-FU IV continuously over 96 hours beginning on days 1, 29, 57, and 85 and cisplatin IV over 1 hour on days 1, 29, 57, and 85. Beginning on day 57, patients receive concurrent radiotherapy. In both arms, radiotherapy is administered daily, 5 days a week, for 5-6.5 weeks. Patients with T3, T4, or N+ lesions or T2 lesions with residual disease receive additional radiotherapy to a reduced field. Patients are followed every 3 months for 1 year, every 6 months for 1 year, and then annually thereafter. PROJECTED ACCRUAL: A total of 650 patients will be accrued for this study within 5 years.