Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the colon or rectum

- No other histological types

- Metastatic, unresectable disease

- No bone metastases only

- Unidimensionally measurable metastatic disease

- No CNS metastases

PATIENT CHARACTERISTICS:

- WHO performance status (PS) 0-2 OR Karnofsky PS 70-100%

- Life expectancy ≥ 12 weeks

- ANC > 1,500/mm³

- Platelet count ≥ 100,000/mm³

- Hemoglobin ≥ 10 g/dL

- Bilirubin ≤ 1.25 times normal (1.5 times normal in presence of hepatic metastases)

- AST and ALT < 3 times normal (5 times normal in presence of hepatic metastases)

- Creatinine < 1.25 times normal

- No proteinuria

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No other cancer in the past 5 years except for carcinoma in situ of the uterine
cervix or basal cell skin cancer

- No hypersensitivity to fluorouracil

- No hypersensitivity to leucovorin calcium, bevacizumab, or their excipients

- No hypersensitivity to Chinese hamster ovarian cell products or other recombinant
humanized or nonhumanized monoclonal antibodies

- No allergy to irinotecan hydrochloride

- No prior reaction to attenuated vaccines (fever, jaundice)

- No poor nutritional status

- No Biermer anemia or other anemia due to vitamin B12 deficiency

- No uncontrolled symptomatic occlusion or subocclusion

- No medullary hypoplasia or severe insufficiency

- No prior chronic intestinal disease

- No Gilbert's syndrome

- No intra-abdominal inflammatory reaction (e.g., gastroduodenal ulcer, diverticulitis,
or colitis)

- No chronic intestinal inflammatory disease

- No thromboembolic arterial condition in the past 6 months, including any of the
following:

- Cardiovascular accident

- Transient ischemic attack

- Myocardial infarction

- No infection or serious noncancerous disease

- No condition that is unstable or would increase risk to the patient, including any of
the following:

- Unstable angina

- Poorly controlled hypertension

- Severe cardiac insufficiency

- Serious arrhythmia

- Bleeding diathesis

- Pulmonary disease at risk of decompensation

- No familial, geographical, social, or psychological condition that would preclude
study participation

- No prisoners or patients without guardians

PRIOR CONCURRENT THERAPY:

- At least 8 weeks since prior surgery

- At least 6 months since prior adjuvant chemotherapy

- At least 1 month since prior palliative chemotherapy

- No prior abdominal or pelvic radiotherapy

- At least 30 days since prior participation in another investigational study

- No prior bevacizumab

- No extensive intestinal resection (e.g., partial colectomy or extensive thin
resection)

- No concurrent warfarin, Hypericum perforatum (St. John's wort), or prophylactic
phenytoin