Letrozole and Goserelin or Leuprolide in Treating Premenopausal Estrogen Receptor-Positive Patients With Stage IV Breast Cancer

DISEASE CHARACTERISTICS:

* Histologically confirmed carcinoma of the breast

  * Metastatic disease
* Measurable disease (i.e., unidimensional by RECIST)
* No rapidly progressing visceral involvement (e.g., liver or lymphangitic lung disease)
* No known marrow involvement as evidenced by diffuse uptake by imaging studies or bone marrow biopsy or aspirate
* No evidence of CNS metastases
* Estrogen- and/or progesterone-receptor positive status confirmed in primary breast tumor or in recent biopsy of metastatic site

PATIENT CHARACTERISTICS:

* Female
* Premenopausal\*, as defined by the following criteria:

  * Less than 12 months from last menstrual period or premenopausal estradiol within the past 12 months
  * No prior bilateral oophorectomy
  * 45 years old or younger with intact ovaries and not a candidate for aromatase inhibitor therapy alone due to the potential for recurrent ovarian function NOTE: \*Women are considered premenopausal after prior hysterectomy if they have intact ovaries and follicular hormone levels consistent with the institutional normal values for the premenopausal state
* Women meeting premenopausal criteria prior to receiving ovarian suppression are eligible
* ECOG performance status 0-2
* Life expectancy ≥ 3 months
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective nonhormonal contraception during and for 12 weeks after discontinuation of study therapy
* ANC ≥ 500 cells/mm³
* Platelet count ≥ 50,000 cells/mm³
* Hematocrit ≥ 28%
* In the absence of liver metastases:

  * AST and ALT ≤ 2.5 times upper limit of normal (ULN)
  * Alkaline phosphatase ≤ 2.5 times ULN
* In the presence of liver metastases:

  * AST and ALT ≤ 5 times ULN
  * Alkaline phosphatase ≤ 5 times ULN
* In the presence of bone metastases:

  * AST and ALT ≤ 10 times ULN
  * Alkaline phosphatase ≤ 10 times ULN
* Total bilirubin ≤ 2 times ULN
* No significant comorbid conditions, including any of the following:

  * Clinically significant cardiac disease not well controlled with medication (e.g., congestive heart failure, symptomatic coronary artery disease, or cardiac arrhythmias)
  * Myocardial infarction within the past 12 months
  * Serious concurrent infection
* No lack of physical integrity of the upper gastrointestinal tract
* No inability to swallow or malabsorption syndrome
* No other carcinoma within the past 5 years except nonmelanoma skin cancer and treated in situ cervical cancer
* No mental illness
* No known hypersensitivity to luteinizing hormone-releasing hormone (LHRH), LHRH-agonist analogues, or any of the components in goserelin

PRIOR CONCURRENT THERAPY:

* No concurrent chemotherapy and/or additional hormonal therapy
* Concurrent trastuzumab (Herceptin®) for patients with HER2 overexpression allowed