This type of cancer is more aggressive than other BC types and has poorer prognosis compared to other BC types (Speers et al., 2017; Kucukzeybek et al., 2018) Recent studies revealed that BC heterogeneity extends to the classic IHC-based subtypes of ER, PR, and HER2 receptors.(Gradishar et al., 2016; Kurozumi et al., 2016) Nowadays, new treatment methods are suggested for TNBC according to new biomarkers and gene expression profile (Burstein et al., 2015; Sarin et al., 2016). Here, ESR1 is linked to breast cancer.