ESR1 and neoplasm: A total of 87 FFPE tumour specimens came from three major IHC subclasses and were composed of 24 ER−/PR−/HER2− (designated TN); 8 ER−/PR−/HER2+ (designated HER2+); 8 ER+/PR-/HER2+ 11 ER+/PR+/HER2+ 13 ER+/PR−/HER2− and 23 ER+/PR+/HER2− (designated HR+).