ERBB2 and invasive ductal breast carcinoma: Of the 20 patients, the pre-NAC median tumor size on MRI was 3.0 cm (interquartile range, 2.0-5.0 cm); 19 patients (95%) had invasive ductal carcinoma, 15 (75%) had stage II cancer, 11 (55%) had ERBB2-positive cancer, and 6 (30%) had triple-negative cancer.