 This is the first neoadjuvant trastuzumab monotherapy study in treatment-naive patients with HER2 overexpressing breast cancers. The clinical efficacy with tumor reductions in some patients presenting with large initial tumors indicates that the monoclonal antibody can be safely administered as a single agent without fear of tumor progression. When the study was first started, the uncertainty of the clinical efficacy of neoadjuvant single agent trastuzumab limited its duration to 3 weeks. It seems likely that the true response rate would have been higher if therapy was continued for several months. Based on these data, longer treatment durations of HER2 targeted therapy, like with GW572016, given as a single agent should be investigated in clinical trials with careful monitoring of patients to assess its activity in this setting. 