PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 No history of glucose-6-phosphate dehydrogenase deficiency Hepatic: Bilirubin no greater than 2.0 mg/dL AST and ALT less than 3 times upper limit of normal Renal: Creatinine no greater than 1.6 mg/dL Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No history of porphyria No active infection No physical or psychological illness that would preclude study