PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 50-100% while on steroids Life expectancy: Not specified Hematopoietic: WBC at least 3,000/mm3 Granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Prothrombin time no greater than 1.5 times upper limit of normal (ULN) Active partial thromboplastin time no greater than 1.5 times ULN Hepatic: Bilirubin no greater than 2 mg/dL AST and ALT no greater than 2 times ULN Renal: Creatinine less than 1.5 mg/dL Cardiovascular: No severe cardiac disease Pulmonary: No severe pulmonary disease Other: No other significant life threatening disease No known glucose-6-phosphate dehydrogenase deficiency or porphyria No other active malignancy No intractable seizures Not pregnant or nursing Effective contraception required of all fertile patients