- Arm A: Patients receive irinotecan hydrochloride IV over 1 hour and leucovorin calcium IV over 2 hours on day 1; fluorouracil IV over 46 hours beginning on day 1; and an oral placebo tablet once daily on days 1-14. Treatment repeats every 14 days for 12 courses in the absence of disease progression or unacceptable toxicity. Patients achieving at least stable disease then receive oral placebo alone once daily in the absence of disease progression or unacceptable toxicity.