In the training cohort, HER2-zero cancers differed significantly from HER2-low/HER2-positive cancers in Ki-67 index, histological grade, clinical T stage, and several ultrasound features, including presence of calcifications, external and internal color Doppler flow imaging (CDFI), internal echo pattern, and posterior acoustic features (all p < .05). This evidence concerns the gene ERBB2 and cancer.