ERBB2 and invasive ductal breast carcinoma: Of these tumors 83 % were invasive ductal carcinomas (no special type); 42 % were grade 2 and 46 % were grade 3: 50 % were ERα– and PR–, 48 % were HER2+ (IHC3+ or HER2 amplified by fluorescence in situ hybridization (FISH)).