PATIENT CHARACTERISTICS: Age: 18 and over (must be 60 or under if receiving higher dose of cytarabine) Performance status: Karnofsky 60-100% Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Bilirubin no greater than 2.0 mg/dL (bilirubin no greater than 3.0 mg/dL and conjugated bilirubin no greater than 0.5 mg/dL if Gilbert's disease and predominantly unconjugated hyperbilirubinemia present) AST no greater than 2.5 times upper limit of normal (ULN) Alkaline phosphatase no greater than 2.5 times ULN Renal: Creatinine clearance at least 40 mL/min (at least 60 mL/min if receiving higher dose of cytarabine) Pulmonary: No clinically significant pulmonary disease Other: Not pregnant No patients who are poor medical risks because of nonmalignant systemic disease No serious, active, uncontrolled infection No prior or concurrent medical status that would make assessing cortical or cerebellar neurologic toxicity difficult