ERBB2 and breast cancer: Luminal BC is another subtype of breast cancer that is categorized into luminal A (ER+ and/or PR+, and HER2-), representing around 60% of BC and associating with a good prognosis, and luminal B (ER+ and/or PR+, and HER2+) which represents 30% of BC and is associated with high ki67 (>14%), a proliferation marker, and a poor prognosis [7].