Classical molecular biomarkers, detected from tumour cells by immunohistochemistry, that define molecular subtypes include oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) (Barba et al. 2021; Beňačka et al. 2022; Dai et al. 2016). This evidence concerns the gene ESR1 and neoplasm.