The subtypes of breast cancer include: luminal A [estrogen receptor (ER) +/ progesterone receptor (PR)+], luminal B (ER+, PR+, HER2/HER2±), and triple negative/basal-like (ER−, PR−, HER2−) (TNBC/BLBC) (2, 3). The gene discussed is ERBB2; the disease is breast cancer.