Human epidermal growth factor receptor 2 (HER2), an oncogene for tumorigenesis, is overexpressed in 15–20% of invasive BC; before the availability of anti-HER2 drugs, HER2-positive (HER2+) BC was associated with an increased risk of visceral metastasis and worse outcomes such as shorted progression-free survival and overall survival [4,5,6,7,8]. Here, ERBB2 is linked to breast cancer.