Gemcitabine Hydrochloride and Genistein in Treating Women With Stage IV Breast Cancer

DISEASE CHARACTERISTICS:

Histologically or cytologically confirmed breast cancer

Stage IV disease
Clinical and/or radiological evidence of metastatic disease

Measurable disease

Prior radiotherapy allowed provided there is ≥ 1 measurable disease site outside the radiation field

No active CNS metastases

Previously treated CNS metastases allowed provided disease is stable for ≥ 3 months without steroids or antiseizure medications

Hormone receptor status:

Not specified

PATIENT CHARACTERISTICS:

Sex

Female

Menopausal status

Not specified

Performance status

SWOG 0-2

Life expectancy

Not specified

Hematopoietic

Absolute neutrophil count ≥ 1,500/mm^3
Platelet count ≥ 100,000/mm^3
Hemoglobin ≥ 10 g/dL

Hepatic

Bilirubin ≤3.0 mg/dL
AST and ALT ≤ 2.5 times upper limit of normal

Renal

Creatinine ≤ 1.5 mg/dL

Other

Not pregnant or nursing
Fertile patients must use effective contraception
No serious systemic disorder that would preclude study compliance
No history of another malignancy except curatively treated carcinoma of the cervix or basal cell or squamous cell skin cancer in complete remission
No unresolved bacterial infection requiring antibiotic treatment
No known HIV-1 positivity

PRIOR CONCURRENT THERAPY:

Biologic therapy

At least 3 weeks since prior biologic therapy

Chemotherapy

Prior adjuvant chemotherapy allowed

Prior adjuvant or neoadjuvant taxane-based therapy or taxane therapy for metastatic disease allowed

Patient must have failed therapy within 2 years after completion of treatment
At least 3 weeks since prior chemotherapy
No more than 2 prior cytotoxic chemotherapy regimens for metastatic disease
No prior gemcitabine hydrochloride
No other concurrent chemotherapy

Endocrine therapy

See Disease Characteristics

At least 2 weeks since prior and no concurrent hormonal therapy

Must have documented disease progression during prior hormonal therapy

Radiotherapy

See Disease Characteristics
At least 4 weeks since prior radiotherapy and recovered
No concurrent radiotherapy

Surgery

At least 3 weeks since prior surgery

Other

At least 3 weeks since prior investigational therapy

At least 1 week since prior soy supplements (e.g., soy-based pills, liquids, or concentrates)

Dietary soy as part of a meal (e.g., tofu) allowed once a week

No concurrent nutritional supplements, herbal agents, or high doses of antioxidants (e.g., vitamins C, D, or E) that may interact with, antagonize, alter, or imitate the potential effects of gemcitabine hydrochloride or genistein

A single daily multivitamin is allowed
No other concurrent immunotherapy
No other concurrent experimental medication
Concurrent anticoagulants, appetite stimulants, and replacement steroids allowed