DISEASE CHARACTERISTICS: Histologically confirmed advanced solid malignancy for which no curative or life-extending therapy exists No prior or concurrent CNS metastases Primary CNS tumors allowed if on a stable dose of steroids at least 2 weeks before study entry No myelodysplastic syndrome

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: More than 12 weeks Hematopoietic: Absolute neutrophil count greater than 1,500/mm3 Platelet count greater than 120,000/mm3 Hemoglobin greater than 8 g/dL Hepatic: Bilirubin normal AST and ALT less than 2.5 times upper limit of normal Renal: Creatinine less then 1.5 mg/dL OR Creatinine clearance greater than 60 mL/min Cardiovascular: No uncontrolled cardiac disease No uncontrolled hypertension Pulmonary: DLCO and vital capacity greater than 80% predicted Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception HIV negative Oral intake at least 1,200 calories per day No recent weight loss of more than 10% actual body weight No serious concurrent illness No uncontrolled infection

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy No concurrent immunotherapy No concurrent immunomodulating agents Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) No other concurrent cytostatic or cytotoxic chemotherapy Endocrine therapy: See Disease Characteristics No concurrent hormonal therapy No concurrent dexamethasone Radiotherapy: At least 3 weeks since prior radiotherapy No prior radiotherapy to more than 25% of bone marrow No concurrent radiotherapy Surgery: At least 3 weeks since prior major surgery