PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 9.0 g/dL Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) AST and ALT no greater than 3 times ULN (no greater than 5 times ULN if liver metastases present) Albumin greater than 2.5 g/dL Renal: Creatinine no greater than ULN Other: No known hypersensitivity to sulfa compounds No known glucose-6-phosphate dehydrogenase deficiency No active or uncontrolled infection No other malignancy within the past 2 years No other severe disease including neurologic or psychiatric disorders that would preclude study Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception