ERBB2 and cancer: We chose to define the different groups by leveraging the following five features: (1) age (≤50, 50–60, ≥60); (2) cancer subtype (luminal, TNBC, HER2+); (3) histological type (invasive carcinoma of no special type (NST), other); (4) tumor grade (I or II, III); and (5) Ki67 (below 15%, above 15%).