DISEASE CHARACTERISTICS:

• Histologically confirmed colorectal cancer

  • Locally recurrent or metastatic disease
  • Previously treated with 1 chemotherapy regimen for recurrent or metastatic disease

• At least 1 unidimensionally measurable lesion

  • At least 20 mm by conventional techniques OR
  • At least 10 mm by spiral CT scan
  • No prior radiotherapy to indicator lesion (clear disease progression or new lesion within a prior radiation port is acceptable)

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• Not specified

Hematopoietic:

• Absolute granulocyte count at least 1,500/mm^3
• Platelet count at least 120,000/mm^3

Hepatic:

• Bilirubin normal
• AST and ALT no greater than 2.5 times upper limit of normal

Renal:

• Creatinine normal OR
• Creatinine clearance at least 60 mL/min

Cardiovascular:

• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia

Pulmonary:

• DLCO at least 80% predicted
• FVC at least 80% predicted
• No history of significant pulmonary disease
• No concurrent symptomatic pulmonary disease (e.g., chronic obstructive pulmonary disorder, chronic asthma)

Other:

• No other malignancy within the past 5 years except adequately treated nonmelanoma skin cancer or curatively treated carcinoma in situ of the cervix
• No other serious illness or medical condition that would preclude study
• No ongoing or active uncontrolled infection
• No history of significant neurologic or psychiatric disorder that would preclude study
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 3 months after study

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 4 weeks since prior immunotherapy
• No concurrent immunotherapy

Chemotherapy:

• See Disease Characteristics
• Prior adjuvant chemotherapy allowed
• No prior nitrosoureas
• No prior second-line chemotherapy for recurrent or metastatic disease
• At least 4 weeks since prior chemotherapy
• No other concurrent chemotherapy

Endocrine therapy:

• No concurrent corticosteroids

Radiotherapy:

• See Disease Characteristics
• Prior radiotherapy as part of primary therapy allowed
• At least 4 weeks since prior radiotherapy
• No concurrent radiotherapy

Surgery:

• Prior surgery as part of primary therapy allowed
• Prior reoperation for recurrent disease allowed
• At least 2 weeks since prior surgery other than biopsy

Other:

• At least 4 weeks since prior investigational agent
• No other concurrent investigational agents or therapy
• No other concurrent anticancer therapy