ERBB2 and breast carcinoma: Common sites for breast metastases are the lungs, liver, bones, and brain.7 The development of metastatic disease is often unpredictable but has been associated with the initial stage at diagnosis and with other tumor characteristics, including receptor status.8 All subtypes of breast cancer on the basis of hormonal and human epidermal growth factor receptor 2 (HER2) receptor status have the potential to become metastatic.7 Other risk factors for metastases include age, nodal status, tumor grade, and size.9