Although many women are effectively treated with specific therapies directed at the estrogen receptor (ER) and human epidermal growth factor type 2 receptor (HER2), 15% of breast cancers do not overexpress hormone receptors (ER and progesterone receptor (PR)) nor HER2 and are known as triple-negative breast cancer (TNBC). The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.