RATIONALE: Bevacizumab may stop the growth of tumor cells by blocking the enzymes necessary for cancer cell growth. Drugs used in chemotherapy such as fluorouracil and leucovorin use different ways to stop tumor cells from dividing so they stop growing or die. Combining bevacizumab with fluorouracil and leucovorin may kill more tumor cells. PURPOSE: Phase II trial to study the effectiveness of combining bevacizumab with fluorouracil and leucovorin in treating patients who have locally advanced or metastatic stage IV colorectal cancer that has progressed after standard chemotherapy.

OBJECTIVES: * Determine the response rate of patients treated with bevacizumab, fluorouracil, and leucovorin calcium for stage IV colorectal cancer that has progressed after standard chemotherapy. * Determine the time to progression and overall survival of patients treated with this regimen. * Determine the safety of administering "bolus" and continuous infusion fluorouracil and leucovorin calcium in patients treated with this regimen. OUTLINE: This is an open-label, multicenter study. Patients receive 1 of 2 treatment regimens. * Regimen I: Patients receive bevacizumab IV on days 1, 15, 29, and 42 (every 2 weeks) and leucovorin calcium (CF) IV over 2 hours and fluorouracil (5-FU) IV bolus on days 1, 8, 15, 22, 29, and 36. * Regimen II: Patients receive bevacizumab as in regimen I and CF IV over 2 hours and 5-FU IV bolus followed by a continuous infusion over 22 hours on days 1, 2, 15, 16, 29, 30, 43, and 44. For both regimens, courses repeat every 8 weeks in the absence of disease progression or unacceptable toxicity. Patients are followed for tumor response and survival. PROJECTED ACCRUAL: Various NCI-designated Clinical Cancer Centers and other medical institutions across the United States will participate in this study. A total of 35-125 patients will be accrued for this study within 3 months.