DISEASE CHARACTERISTICS:

* Histologically or cytologically confirmed colorectal adenocarcinoma

* Stage IV (metastatic) disease
* Not curable by surgery or radiotherapy
* Must have received prior standard chemotherapy regimens, including oxaliplatin and irinotecan, and meet both of the following criteria:

* Disease progression during or after irinotecan-based chemotherapy for metastatic disease OR relapsed disease within 6 months after adjuvant irinotecan-based therapy
* Disease progression during or after oxaliplatin-based chemotherapy for metastatic disease OR relapsed disease within 6 months after adjuvant oxaliplatin-based therapy
* No brain metastases

PATIENT CHARACTERISTICS:

Age

* 18 and over

Performance status

* ECOG 0-2 OR
* Karnofsky 60-100%

Life expectancy

* Not specified

Hematopoietic

* Absolute granulocyte count at least 1,500/mm\^3
* Platelet count at least 100,000/mm\^3
* Hemoglobin at least 9 g/dL (transfusion allowed)
* No evidence of bleeding diathesis or coagulopathy

Hepatic

* Bilirubin no greater than 1.5 mg/dL
* AST less than 5 times upper limit of normal (ULN)
* Alkaline phosphatase less than 5 times ULN
* PT and INR no greater than 1.5 times ULN
* PTT no greater than ULN

Renal

* Creatinine no greater than 1.5 times ULN
* Proteinuria less than grade 1 OR
* Proteinuria less than 500 mg/24 hours

Cardiovascular

* No prior stroke
* No uncontrolled high blood pressure
* No symptomatic congestive heart failure
* No unstable angina pectoris
* No cardiac arrhythmia
* No myocardial infarction within the past 6 months
* No New York Heart Association class III or IV heart disease
* No thromboembolism within the past 6 months

Other

* Chemonaive
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for at least 3 months after study participation
* No significant traumatic injury within the past 6 weeks
* No prior allergic reaction attributed to compounds of similar chemical or biological composition to bevacizumab or other study agents
* No active infection
* No psychiatric illness or social situation that would preclude study compliance
* No serious nonhealing wound (including wounds healing by secondary intention), ulcer, or bone fracture
* No CNS disease, including either of the following:

* Primary brain tumor
* Seizures not controlled with standard medical therapy

PRIOR CONCURRENT THERAPY:

Biologic therapy

* At least 8 weeks since prior monoclonal antibody therapy
* No prior bevacizumab

Chemotherapy

* See Disease Characteristics

Endocrine therapy

* Not specified

Radiotherapy

* At least 4 weeks since prior major radiotherapy (e.g., chest or bone palliative radiotherapy)

Surgery

* More than 6 weeks since prior major surgical procedure or open biopsy
* More than 7 days since prior fine needle aspiration or core biopsy
* No concurrent surgery

Other

* Recovered from prior therapy
* At least 3 weeks since prior cytotoxic agents
* No concurrent therapeutic anticoagulation

* Prophylactic anticoagulation of venous access devices allowed provided PT/INR or PTT criteria are met
* No concurrent chronic aspirin (greater than 325 mg/day) or nonsteroidal anti-inflammatory drugs
* No concurrent combination antiretroviral therapy for HIV-positive patients
* No other concurrent investigational or commercial agents for the malignancy