Fluorouracil and Biological Therapy in Treating Patients With Metastatic Kidney or Colorectal Cancer

DISEASE CHARACTERISTICS: Histologically confirmed metastatic renal cell carcinoma or colorectal carcinoma Failed prior standard or salvage therapy OR Ineligible for standard therapy due to concurrent illness OR Declined standard therapy Bidimensionally measurable disease (by CT scan or MRI) outside prior irradiation port unless documented disease progression after radiotherapy No untreated or unstable treated brain metastasis PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: More than 3 months Hematopoietic: WBC at least 4,000/mm3 Platelet count at least 100,000/mm3 Total granulocyte count at least 2,000/mm3 Hemoglobin at least 10 g/dL No coagulation disorders such as thrombophlebitis Hepatic: Bilirubin no greater than 2.5 mg/dL SGOT/SGPT less than 3 times upper limit of normal (ULN) Alkaline phosphatase less than 3 times ULN PT/PTT no greater than 1.5 times control Hepatitis B surface antigen negative Renal: Creatinine no greater than 2.0 mg/dL Cardiovascular: No active ischemia and/or ejection fraction less than 45% No unstable angina No uncontrolled congestive heart failure Pulmonary: FEV1 or FVC greater than 65% of predicted No uncontrolled pulmonary embolism Other: No other prior malignancy within the past 5 years except resected basal cell carcinoma or carcinoma in situ of the cervix No active systemic infection No autoimmune disease No uncontrolled thyroid abnormalities No other major medical illness HIV negative Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: See Disease Characteristics Biologic therapy: More than 1 month since prior biologic therapy or immunotherapy Chemotherapy: More than 1 month since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) Endocrine therapy: At least 4 weeks since prior steroid therapy or steroid-containing compounds At least 2 weeks since prior topical or inhaled steroids No concurrent steroids Radiotherapy: More than 1 month since prior radiotherapy, interstitial brachytherapy, or radiosurgery Surgery: Not specified