Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed invasive breast carcinoma

- Stage IV disease

- No locally recurrent resectable disease

- No symptomatic brain metastases

- History of brain metastases allowed provided the patient is clinically stable
for > 3 weeks after completion of radiotherapy AND is not taking steroids or
therapeutic anticonvulsants that are CYP3A4 modifiers

- Hormone receptor status:

- Estrogen receptor and/or progesterone receptor positive tumor by
immunohistochemistry (IHC)

PATIENT CHARACTERISTICS:

- Pre- or post-menopausal

- ECOG performance status 0-1

- Life expectancy ≥ 6 months

- ANC ≥ 1,250/mm^3

- Platelet count ≥ 100,000/mm^3

- Creatinine ≤ 1.5 times upper limit of normal (ULN)

- Bilirubin ≤ 1.5 times ULN (≤ 3 times ULN if liver metastasis is present)

- For patients with Gilbert syndrome, direct bilirubin will be measured instead of
total bilirubin

- SGOT and SGPT ≤ 1.5 times ULN (≤ 3 times ULN if liver metastasis is present)

- Alkaline phosphatase ≤ 1.5 times ULN (≤ 3 times ULN if liver metastasis is present)

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective barrier contraception during and for 3 months
after completion of study therapy

- Able to swallow and retain oral medication

- Baseline QTc ≤ 450 msec

- No other invasive cancer within the past 5 years except for completely resected basal
cell or squamous cell skin cancer or successfully treated cervical carcinoma in situ

- No malabsorption syndrome significantly affecting gastrointestinal function

- No diabetes, fasting glucose > 150mg/dL, or receiving ongoing anti-hyperglycemic
therapies

- No concurrent uncontrolled illness including, but not limited to, any of the
following:

- Ongoing or active infection requiring parenteral antibiotics

- Impaired lung function (i.e., COPD or lung conditions requiring oxygen therapy)

- Symptomatic congestive heart failure (NYHA class III or IV heart disease)

- Unstable angina pectoris, angioplasty, stenting, or myocardial infarction within
the past 6 months

- Uncontrolled hypertension, defined as systolic BP > 180 mm Hg or diastolic BP >
100 mm Hg on two consecutive measurements taken ≥ 1 week apart, despite adequate
medical support

- Clinically significant cardiac arrhythmia (multifocal premature ventricular
contractions, bigeminy, trigeminy, or ventricular tachycardia that is
symptomatic or requires treatment)

- Psychiatric illness and/or social situation that would compromise patient safety
or limit compliance with study requirements, including maintenance of a
compliance/pill diary

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- Recovered from prior therapy

- At least 2 weeks since prior investigational drugs

- No more than 4 prior chemotherapy treatments in the metastatic setting

- Does not include endocrine therapy or single-agent biologic therapy

- No concurrent CYP3A4 or CYP1A2 modifiers

- No other concurrent anticancer therapy, including chemotherapy, radiotherapy,
surgery, immunotherapy, hormonal therapy, or biologic therapy

- Concurrent radiotherapy to painful bone metastases or areas of impeding bone
fracture allowed provided radiotherapy is initiated before study therapy