Inclusion Criteria:

- Histologically confirmed metastatic adenocarcinoma of the breast

- HER2 nonoverexpressed (0-1+) OR overexpressed (2-3+)

- Measurable or evaluable disease

- Prior brain metastases responsive to treatment of radiotherapy and/or surgery allowed
(cannot be only site of metastases)

- Age 18 and over

- Female

- Fertile women must use effective contraception

- Eastern Cooperative Oncology Group performance status of 0,1,or 2

- The following lab values obtained at least 4 weeks prior to registration: granulocyte
count at least 1,500/mm^3, platelet count at least 100,000/mm^3, SGOT no greater than
2.5 times upper limit of normal, bilirubin normal, and creatinine no greater than 1.5
mg/dL

- Left ventricular ejection fraction at least lower limit of normal (LLN)

- Prior adjuvant chemotherapy allowed if completed 6 months before metastasis

- Prior endocrine therapy in either a metastatic or adjuvant setting, but patients must
have been off such therapy for at least 2 weeks prior to registration

- Prior radiotherapy allowed only to conserved breast, postmastectomy chest wall with
or without internal mammary lymph node chain (IMN), or field containing less than 25%
bone marrow

- At least 2 weeks since prior radiotherapy

- At least 2 weeks since surgery (including mastectomy) and recovered

Exclusion Criteria:

- Prior deep venous thrombosis or thromboembolic condition

- Prior myocardial infarction or congestive heart failure

- Arrhythmia requiring medication

- Hypertension or systolic or diastolic dysfunction

- Ventricular hypertrophy or conduction abnormality

- Prior pulmonary thromboembolism

- Other malignancy within the past 5 years except curatively treated carcinoma in
situ of the cervix or basal cell or squamous cell carcinoma of the skin

- Pregnant or nursing

- Prior trastuzumab (Herceptin™)

- Prior chemotherapy for advanced or local/regional recurrent disease

- Prior anthracyclines or anthracenediones

- Prior photon IMN treatment

- Concurrent radiotherapy