ESR1 and neoplasm: One hundred twenty-seven (85.2%) patients had unifocal presentations, 69 (46.3%) of tumor foci were in the upper outer quadrant (UOQ), 122 (81.9%) of all tumors were ductal carcinoma, 81 (54.4%) patients had histologically grade 2 carcinomas, 135 (90.6%) of all patient tumors were ER-positive, HER2-negative, and six (4%) were ER-positive, HER2-positive.