ERBB2 and triple-negative breast carcinoma: Triple-negative breast cancer accounts for about 10–15% of breast cancers, HER2-positive (HER2+) breast cancer accounts for 15–20% of breast cancers, and hormone receptor-positive (HR+) breast cancer (covering Luminal A and Luminal B types) is the most common subtype, accounting for about 70–75% of all breast cancer cases.