- Arm II: Patients receive conventional RT once daily, 5 days a week for 25 days. Patients receive fluorouracil IV continuously over 5 days a week concurrently with RT. Patients receive irinotecan IV over 1 hour (immediately prior to RT dose) once weekly for 4 weeks. Patients with clinical stage T3 or fixed T4 disease also receive a lower boost dose of RT to tumor.