ESR1 and triple-negative breast carcinoma: The main subtypes that have been discovered are HER2-enriched (ER-, PR-, HER2+), luminal A (ER+, PR+, HER2-, and Ki-67< 20%), luminal B (ER+, PR+, HER2-, and Ki-67 ≥ 20% or ER+, PR+, and HER2+), and basal-like/triple-negative breast cancer (TNBC) (ER-, PR-, HER2-).