Study of Faslodex +/- Concomitant Arimidex v Exemestane Following Progression on Non-steroidal Aromatase Inhibitors

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