SarCNU in Treating Patients With Recurrent or Metastatic Colorectal Cancer

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