Breast cancer is the most common cancer in women worldwide. In 2011, an estimated 230,000 women were diagnosed with breast cancer in the USA alone, with an estimated 40,000 deaths, making it the second most common cause of cancer-related death in women [1]. The human EGF receptor 2 (HER2) is a cell-membrane tyrosine kinase receptor member of the EGF receptor family that is overexpressed in approximately 15–25% of primary human breast cancers, and is associated with poor clinical outcomes and aggressive tumor progression [2]. In a study of 965 patients with T1, node-negative breast cancer, when compared with patients with HER2-negative disease, there was a significantly worse 5-year rate of recurrence-free survival (77–94%) in patients with HER2-positive cancer [2].