ESR1 and breast carcinoma: Epidemiological and clinical data show that the ER plays an important role in breast cancer development.125, 126, 127 More than 65% of all breast cancers are ER‐positive.128 Because BPA is suggested as a synthetic estrogen and has the potential to induce cell proliferation by activating ERs, the primary mechanism of BPA‐stimulated carcinogenesis in breast cancer can be attributed to its estrogenic activity.7 BPA acts through both estrogen‐dependent and independent pathways.