PATIENT CHARACTERISTICS: Age: 18 and over Menopausal status: Not specified Performance status: Karnofsky 70-100% Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 50,000/mm3 Hepatic: Bilirubin no greater than 2 times upper limit of normal (ULN) AST and ALT no greater than 2 times ULN Renal: Creatinine no greater than 2.0 mg/mL Other: No history of porphyria No history of G6PD deficiency HIV negative No other major medical illnesses No major psychiatric impairment Not pregnant or nursing Negative pregnancy test