PATIENT CHARACTERISTICS: Age: Over 15 Performance status: 0-2 Life expectancy: Not specified Hematopoietic: See Disease Characteristics Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT no greater than 2 times upper limit of normal Renal: Creatinine no greater than 1.5 mg/dL Other: Not pregnant or nursing Fertile patients must use effective contraception Free of any evidence of prior cancer for at least 12 months