Exemestane Compared With Tamoxifen in Treating Women With Locally Recurrent or Metastatic Breast Cancer

DISEASE CHARACTERISTICS:

* Histologically or cytologically proven adenocarcinoma of the breast that is metastatic and progressive or locally recurrent and inoperable
* At least one bidimensionally measurable or evaluable lesion

  * Lytic bone lesions on x-ray/CT scan, surrounded by calcified bone, and at least 1 cm
  * Bidimensionally measurable extraosseous disease required for patients on bisphosphonates
  * The following are not considered evaluable:

    * Previously irradiated lesions
    * Lymphangitic spread
    * Ascites
    * Blastic bone lesions
    * Pleural effusions
* No rapidly progressive disease for which hormonal therapy is not indicated
* No massive visceral disease (i.e., more than one third of any organ)
* No brain metastases
* Hormone receptor status:

  * Estrogen receptor positive or progesterone receptor positive, defined by 1 of the following:

    * At least 10 femtomoles H3-estrogen or at least 20 femtomoles
    * H3 progesterone binding per mg of cytosol protein by DCC or sucrose density method
    * At least 0.10 femtomoles H3-estrogen or at least 0.20 femtomoles
    * H3-progesterone binding per mg of DNA by IF/EIA technique
    * Positive immunohistochemistry noted on pathology report
  * Unknown receptor status eligible provided:

    * Disease-free interval of at least 2 years since adjuvant therapy or initial surgery (if no adjuvant therapy), including most recently treated tumor in bilateral breast cancer if status unknown in one primary tumor

PATIENT CHARACTERISTICS:

Age:

* 18 and over

Sex:

* Female

Menopausal status:

* Postmenopausal by 1 of the following:

  * Natural menopause and more than 1 year since last menstrual period (LMP)
  * Radiation-induced oophorectomy and more than 1 year since LMP
  * Chemotherapy induced menopause if:

    * At least 1 year since LMP (+ 1 year post-tamoxifen)
    * Serum FSH and LH and plasma estradiol levels in postmenopausal range
    * LHRH-induced amenorrhea
  * Surgical castration

    * Patients under age 56 with prior hysterectomy and 1 or both ovaries intact or tamoxifen-induced amenorrhea with at least 12 months since prior tamoxifen must have postmenopausal serum FSH and LH and plasma estradiol concentrations

Performance status:

* ECOG (WHO) 0-2

Hematopoietic:

* Absolute neutrophil count at least 1,500/mm\^3
* Platelet count at least 100,000/mm\^3

Hepatic:

* Bilirubin less than 1.5 times upper limit of normal (ULN)
* SGOT/SGPT less than 2.5 times ULN (less than 5 times ULN with liver metastases)

Renal:

* Creatinine less than 1.5 times ULN

Cardiovascular:

* No deep venous thrombosis

Other:

* No mental incapacitation
* No severe concurrent disease
* No prior or concurrent malignancy except curatively treated carcinoma in situ of the cervix or basal cell or squamous cell skin cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy:

* No concurrent immunotherapy

Chemotherapy:

* See Disease Characteristics
* At least 3 weeks since chemotherapy for metastatic disease and recovered
* No more than 1 prior chemotherapy regimen for metastatic disease
* Prior adjuvant chemotherapy allowed if disease free for at least 6 months
* No concurrent chemotherapy

Endocrine therapy:

* No prior hormonal therapy for advanced disease (e.g., tamoxifen or LHRH agonists)
* Prior adjuvant tamoxifen allowed if disease free for at least 6 months
* No other concurrent hormonal therapy, including steroids

Radiotherapy:

* Recovered from toxic effects of prior radiotherapy
* Concurrent palliative radiotherapy, including whole brain irradiation, allowed

Surgery:

* See Disease Characteristics
* No prior ovariectomy for advanced disease

Other:

* No other concurrent investigational drugs
* Concurrent bisphosphonates allowed if short term (7 days) for hypercalcemia due to suspect tumor flare or if on prior bisphosphonates with bidimensionally measurable extraosseous lesion