ERBB2 and cancer: On the other hand, HER2-positive (HER2+) breast cancers usually occur in younger women, grow more invasively, and prior to the advent of targeted therapy, posed a higher risk of recurrence than HER2-negative (HER2-) breast cancers, partly because of the overexpression of HER2/neu protein (human epidermal growth factor receptor 2, also known as ERBB2) in these cancers.