Irinotecan, Fluorouracil, and Leucovorin in Treating Patients With Advanced Gastrointestinal Cancer

RATIONALE: Drugs used in chemotherapy, such as irinotecan, fluorouracil, and leucovorin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells.
PURPOSE: This phase I trial is studying the side effects and best dose of irinotecan when given together with fluorouracil and leucovorin in treating patients with advanced gastrointestinal cancer.