DISEASE CHARACTERISTICS:

Inclusion criteria:

• Histologically confirmed adenocarcinoma of the colon or rectum

  • Metastatic disease
  • Not surgically curable
• Homozygous for allele UGT1A1*28, the promoter of the gene coding for UGT1A1 (genotype 7/7)
• Measurable and/or evaluable disease

Exclusion criteria:

• Original tumor not removed
• CNS metastases
• Secondary localized cerebral tumors

PATIENT CHARACTERISTICS:

Inclusion criteria:

• WHO performance status 0-2
• ANC ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• Hemoglobin ≥ 9 g/dL
• Creatinine > 1.5 mg/dL
• Total bilirubin ≤ 1.5 times normal
• Alkaline phosphatase ≤ 2.5 times normal (5 times normal if liver involvement)
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients of must use effective contraception

Exclusion criteria:

• Progressive gastroduodenal ulcer, prior hemorrhagic ulcer, or perforation in the past 6 months
• Enteropathy or chronic diarrhea
• Chronic inflammatory intestinal disease
• Intestinal obstruction

• Active cardiac disease including any of the following:

  • Uncontrolled hypertension
  • Myocardial infarction in the past 12 months
  • Serious angina
  • NYHA class II-IV congestive heart failure
  • Severe arrhythmia (even if treated)
  • Peripheral vascular disease ≥ grade 2
• Unhealed wound, ulcer, or severe bone fracture
• Bleeding disorder or coagulopathy
• Severe uncontrolled infection or medical condition
• Proteinuria > 500 mg/24 hours
• Other malignancy within the past 5 years except basal cell skin cancer or curatively treated carcinoma in situ of the cervix
• Known dihydropyrimidine dehydrogenase deficiency
• Severe traumatic injury within the past 4 weeks

PRIOR CONCURRENT THERAPY:

Inclusion criteria:

• At least 2 weeks since prior radiotherapy

Exclusion criteria:

• Prior chemotherapy for metastatic disease except adjuvant chemotherapy completed > 6 months ago
• Prior irinotecan hydrochloride or bevacizumab
• Major surgery or biopsy within the past 4 weeks
• Major surgery planned
• Puncture in the past week
• Chronic aspirin (> 325 mg/day) or NSAIDs
• Concurrent antifungal azoles (e.g., ketoconazole, fluconazole, itraconazole)
• Concurrent phenytoin (as in yellow fever vaccine)
• Concurrent Hypericum perforatum (St. John's wort)

• Oral or parenteral coagulant in the past 10 days and during study therapy

  • Warfarin allowed provided INR < 1.5