Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed locally recurrent or
metastatic breast cancer not amenable to surgery or radiotherapy Measurable or evaluable
disease No prior radiotherapy to only target lesion Disease progression after no more than
2 prior chemotherapy treatments for metastatic disease No active CNS metastasis Prior CNS
metastasis allowed with no evidence of active disease Hormone receptor status: Not
specified

PATIENT CHARACTERISTICS: Age: Not specified Menopausal status: Not specified Performance
status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Absolute granulocyte
count greater than 1,500/mm3 Hemoglobin greater than 9.0 g/dL Platelet count greater than
100,000/mm3 Hepatic: Bilirubin no greater than 2.0 mg/dL AST/ALT no greater than 3 times
upper limit of normal (ULN) (no greater than 5 times ULN in case of liver metastases)
Renal: Creatinine no greater than 2.0 mg/dL Other: Not pregnant or nursing Negative
pregnancy test Fertile patients must use effective contraception Must be able to have
daily fluid intake of at least 3 liters No concurrent active infection No other prior
malignancy in past 5 years except adequately treated basal cell carcinoma of the skin or
carcinoma in situ of the cervix

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease
Characteristics No prior irinotecan, topotecan, or other camptothecin analogues At least 3
weeks since prior chemotherapy Endocrine therapy: No concurrent corticosteroids to control
CNS disease Radiotherapy: See Disease Characteristics At least 2 weeks since prior
radiotherapy Surgery: At least 4 weeks since prior major surgery