Invasive ductal carcinoma was more common in ER-negative/PR-positive (77.9%) and ER-negative/PR-negative (81.5%) tumors, whereas ILC and mixed IDC/ILC were more common in ER-positive/PR-positive (17.7%) and ER-positive/PR-negative (17.5%) tumors. Here, ESR1 is linked to breast ductal adenocarcinoma.