Protocol for Herceptin as Adjuvant Therapy With Reduced Exposure to Chemotherapy (PHARE-C)

Inclusion Criteria: * Histologically confirmed adenocarcinoma of the breast, nonmetastatic disease and non operated tumor * Without suspicious axillary nodes * Tumor size \< 30 mm * Eligibility to receive a weekly paclitaxel based chemotherapy for this cancer * Left Ventricular Ejection Fraction (LVEF) obtained and \> 50% as measured by echocardiography (Simpson method) or multigated acquisition scan (MUGA) at 3 months (-/+ 1 month) * Overexpression of HER-2 in the invasive component of the primary tumor as indicated by one of the following: 3+ by immunohistochemistry (IHC) 2+ by IHC and confirmation by fluorescent in situ hybridization (FISH) or chromogenic in situ hybridization (CISH) * With signed Informed consent Exclusion Criteria: * Previous anti-HER2 treatment (except for HERCEPTIN) * Cardiac disease or other medical conditions preventing trastuzumab administration * Known allergy to trastuzumab, murine proteins or other excipients * Pregnant or breastfeeding women * Patients that are not able to comply to the protocol assessments for geographic, social or psychological reasons