DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed locally advanced, locally recurrent, or metastatic colorectal adenocarcinoma not curable by surgery or radiotherapy

• Progressive disease following:

  • One prior fluorouracil based chemotherapy regimen for metastatic disease OR
  • Failure during or within 6 months after fluorouracil based adjuvant therapy
• Measurable or evaluable disease
• No CNS metastases or carcinomatous meningitis

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• At least 12 weeks

Hematopoietic:

• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3
• Hemoglobin at least 9 g/dL (transfusion allowed)

Hepatic:

• Bilirubin no greater than 1.5 mg/dL
• AST no greater than 5 times upper limit of normal (ULN)
• Alkaline phosphatase no greater than 5 times ULN

Renal:

• Creatinine no greater than 1.5 times ULN

Cardiovascular:

• No uncontrolled high blood pressure
• No unstable angina
• No symptomatic congestive heart failure
• No myocardial infarction with the past 6 months
• No serious uncontrolled cardiac arrhythmias
• No New York Heart Association class III or IV heart disease

Pulmonary:

• No pleural effusion or ascites that cause respiratory compromise (e.g., dyspnea grade 2 or greater)
• No interstitial pneumonia or extensive and symptomatic interstitial fibrosis of the lung

Other:

• Not pregnant or nursing
• Fertile patients must use effective contraception
• Fluent in English
• No active or uncontrolled infection
• No other prior malignancy within the past 5 years, except:
• Adequately treated basal or squamous cell skin cancer
• Adequately treated noninvasive carcinomas
• No sensory neuropathy grade 2 or greater
• No uncontrolled colonic or small bowel disorders (greater than 3 loose stools daily)

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No concurrent sargramostim (GM-CSF)

Chemotherapy:

• At least 4 weeks since prior chemotherapy and recovered
• No more than 1 prior chemotherapy regimen for advanced colorectal cancer
• No prior irinotecan or other camptothecin derivative (e.g., topotecan)
• No prior oxaliplatin
• No other concurrent investigational chemotherapy agents

Endocrine therapy:

• Not specified

Radiotherapy:

• At least 4 weeks since prior major radiotherapy
• No prior radiotherapy to greater than 25% of bone marrow

Surgery:

• At least 4 weeks since prior major surgery and recovered
• At least 2 weeks since prior minor surgery and recovered