ESR1 and invasive ductal breast carcinoma: The majority of patients were 30–39 years of age; married; Caucasian; carrying health insurance; diagnosed with T1–2 stage, grade III, undifferentiated, invasive ductal carcinoma, ER-positive, and N0–N1 stage tumors; had undergone mastectomy; and had received chemotherapy (Supplementary eTable 1 in the Supporting Materials).