PATIENT CHARACTERISTICS: Age: Not specified Performance status: ECOG 0-2 Life expectancy: At least 3 months Hematopoietic: WBC at least 4,000/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL Renal: Creatinine no greater than 1.5 mg/dL Creatinine clearance at least 50 mL/min Cardiovascular: Systolic blood pressure at least 90 mm Hg No severe heart decompensation No clinically significant cardiac arrhythmia on EKG No inability to tolerate bradycardia Other: No active, uncontrolled infection No nonmalignant systemic disease Not pregnant or nursing Effective contraception required of fertile patients