Gallen International Breast Cancer Conference, breast cancer can be differentiated based on molecular subtypes such as luminal A, which is characterized by estrogen receptor (ER) positivity and progesterone receptor (PR) positivity (where ER and PR status are jointly assessed as hormone receptor [HR] status), and human epidermal growth factor receptor 2 (HER 2) negativity. Here, ERBB2 is linked to breast cancer.