OBJECTIVES: I. Compare the median survival in patients with metastatic colorectal cancer treated with fluorouracil and leucovorin calcium with or without SU5416. II. Compare the time to progression, duration of response, and objective response in these patients on these two regimens. III. Compare the percentage 6 month, 9 month, and one year survival of these patients on these two regimens. IV. Compare the time to treatment failure in these patients on these two regimens. V. Determine the health related quality of life of these patients on these two regimens. VI. Compare the palliative and biologic effects of SU5416 in these patients. VII. Determine the safety and tolerability of fluorouracil and leucovorin calcium plus SU5416 in these patients.