OUTLINE: This is a randomized, multicenter study. Patients are stratified by participating institution and measurable or evaluable disease. Patients are randomized to receive either a 2 hour continuous infusion of irinotecan or a 2 hour continuous infusion of oxaliplatin on day 1. All patients receive a 2 hour continuous infusion of leucovorin calcium followed by IV bolus and 48 hour continuous infusion of fluorouracil on days 1 and 2. Courses are repeated every 2 weeks. Patients will receive the alternate treatment if disease progression or unacceptable toxicity occurs on their initial treatment. Patients are followed every 3 months after end of treatment.