ERBB2 and breast cancer: In their studies, Bian et al and Guo et al first distinguished HER2-positive from HER2-negative (HER2-low and HER2-zero) breast cancers, and their models achieved AUCs of 0.760 to 0.763 in the validation cohort, further distinguishing HER2-low from HER2-zero breast cancers, AUCs of 0.711 to 0.750 were achieved in the validation cohort.