Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed adenocarcinoma of the breast

- Locally advanced or metastatic disease

- Metastatic disease must be measurable or evaluable

- Patients with bone only metastases are eligible provided there is an evaluable
site of bone metastasis that can be followed by x-ray, MRI, or CT scan

- Relapsed or progressed during prior treatment with single-agent nonsteroidal
aromatase inhibitor (NSAI)*, meeting either of the following criteria:

- NSAI given as adjuvant therapy that lasted ≥ 12 months

- Achieved an objective complete response, partial response, or stable disease
that lasted ≥ 6 months after prior first-line therapy with NSAI for locally
advanced or metastatic disease

- Chemotherapy as part of the first-line therapy given before initiation of
NSAI allowed NOTE: *Patients are required to continue to take NSAI until
beginning of study treatment.

- No rapidly progressive visceral disease (i.e., lymphangitis carcinomatosa or diffuse
hepatic involvement)

- Hormone receptor status:

- Estrogen receptor (ER) and/or progesterone receptor positive tumor

- No ER-unknown disease

PATIENT CHARACTERISTICS:

Sex

- Female

Menopausal status

- Postmenopausal, as defined by 1 of the following criteria:

- Age 60 and over

- Age 45 to 59 AND ≥ 12 months since last menstrual period with no prior
hysterectomy

- Any age with prior bilateral oophorectomy

Performance status

- WHO 0-2

Life expectancy

- More than 3 months

Hematopoietic

- Neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- No thrombocytopenia

- Hemoglobin ≥ 10 g/dL

Hepatic

- AST and ALT ≤ 2.5 times upper limit of normal (ULN)

- Alkaline phosphatase ≤ 5 times ULN (unless due to bone metastases)

- No liver disease

Renal

- Creatinine < 1.97 mg/dL

Other

- No other malignancy within the past 5 years except adequately treated basal cell or
squamous cell skin cancer or carcinoma in situ of the cervix

PRIOR CONCURRENT THERAPY:

Chemotherapy

- See Disease Characteristics

- Prior neoadjuvant or adjuvant chemotherapy allowed

Endocrine therapy

- See Disease Characteristics

- Prior tamoxifen as neoadjuvant or adjuvant therapy allowed

- No systemic corticosteroids that lasted > 15 days within the past 4 weeks

Other

- More than 4 weeks since prior investigational drugs

- Concurrent bisphosphonates for bone metastases allowed provided bisphosphonate
therapy has been established for ≥ 6 months

- Concurrent initiation of bisphosphonate allowed provided patient has soft tissue
or visceral metastases as the measurable or evaluable target lesion

- No concurrent anticoagulant therapy

- No concurrent unlicensed noncancer investigational agents