ESR1 and neoplasm: Luminal-like tumours, including luminal-A (estrogen receptor (ER+)/progesterone receptor (PR+)/oncogene Erb-B2 (HER2−) and luminal-B (ER+/PR−/HER2+) tumours, are the most prevalent subtypes of BC, comprising 40% and 20% of BC cases, respectively, with good prognoses [4,5].