According to these biomarkers, BC can be categorised into at least four subtypes: hormone receptor‐positive (HR+)/HER2‐negative (HER2−), HR+/HER2‐positive (HER2+ or HER2‐enriched), HR−/HER2+ and triple‐negative breast cancer (TNBC) [4, 5]. This evidence concerns the gene HR and breast cancer.