ERBB2 and breast cancer: Over the years, with advances in molecular medicine, the incorporation of markers, such as oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), have proven to be especially valuable not only for stratifying certain types of breast cancers in distinct functional groups [3], but also for planning and predicting the outcome with respect to specific treatment options [4,5].