Inclusion Criteria:

- Histologically confirmed invasive carcinoma of the breast

- Tumors must be less than or equal to 3cm in greatest dimension

- Must have node-negative breast cancer according to teh AJCC 7th edition

- ER/PR determination is required. ER- and PR-assays should be performed by
immunohistochemical methods

- HER-2 positive: IHC 3+ or FISH >2

- Bilateral breast cancers that individually meet eligibility criteria are allowed

- Patients should have tumor tissue available, and a tissue block of sufficient size to
make 15 slides must be sent to DFCI for testing

- Less than or equal to 84 days from mastectomy or from axillary dissection or sentinel
node biopsy if the patient's most extensive breast surgery was a breast-sparing
procedure

- All tumor should be removed by either a modified radical mastectomy or a segmental
mastectomy (lumpectomy), with either a sentinel node biopsy or axillary dissection

- 18 years of age or older

- ECOG Performance Status of 0 or 1

- Adequate bone marrow function, hepatic function, and renal function as outlined in
protocol

- Left ventricular ejection fraction of greater than or equal to 50%

- Willingness to discontinue any hormonal agent prior to registration and while on
study

- Willingness to discontinue sex hormonal therapy, e.g. birth control pills, prior to
registration and while on study

- Patients with a history of ipsilateral DCIS are eligible if they were treated with
wide-excision alone, without radiation therapy

- Patients undergoing breast conservation therapy must not have any contraindications
to radiation therapy

Exclusion Criteria:

- Pregnant or nursing women

- Locally advanced tumors at diagnosis, including tumors fixed to the chest wall, peau
d'orange, skin ulcerations/nodules, or clinical inflammatory changes

- History of prior chemotherapy in past 5 years

- History of prior trastuzumab therapy

- Active, unresolved infection

- Prior history of any other malignancy in the past 5 years, except for early stage
tumors of the skin or cervix treated with curative intent

- Sensitivity to benzyl alcohol

- Grade 2 or greater neuropathy per NCI's CTCAv3.0. (Exception: Any chronic neurologic
disorder will be looked at on a case-by-case basis by the study chair).

- Active cardiac disease as outlined in protocol.