The molecular subtypes of breast tumor based on ER status, progesterone-receptor (PR) status, and human epidermal growth factor 2 (HER2) oncogene expression, followed by five specific combinations (ER+, ER–, ER+/PR+, ER–/PR–, and ER–/PR–/HER2–). This evidence concerns the gene ESR1 and breast neoplasm.