Inclusion Criteria:

- Age >= 18 years.

- Performance status (World Health Organization [WHO]) < 3

- Adequate bone marrow function (absolute neutrophil count > 1000/mm^3, platelet
count > 100000/mm^3, hemoglobin > 9 gr/mm^3)

- Adequate liver (bilirubin < 1.5 times upper limit of normal and SGOT/SGPT < 2 times
upper limit of normal) and renal function ( creatinine < 2 mg/dl)

- Adequate cardiac function (left ventricular ejection fraction [LVEF] > 50%).

- Informed consent

- Histologically or cytologically confirmed breast adenocarcinoma

- Prior surgical excision of the primary breast tumor

- Prior completion of standard adjuvant chemotherapy and/or radiotherapy

- Locally advanced disease after the completion of neo-adjuvant chemotherapy, surgical
excision and radiotherapy provided that there was no evidence of local or metastatic
disease

- Absence of any clinical or laboratory evidence of metastatic disease

- Detection of CTCs and/or DTCs (when it could be feasible) before the initiation
and/or after the completion of adjuvant chemotherapy and/or radiotherapy

- Expression of HER2/c-neu on the primary tumor is not mandatory

Exclusion Criteria:

- Other invasive malignancy within the past 5 years except nonmelanoma skin cancer

- Other concurrent uncontrolled illness

- Psychiatric illness or social situation that would preclude study compliance

- Pregnant or nursing

- Positive pregnancy test

- History of allergic reaction attributed to trastuzumab (HERCEPTIN)