ERBB2 and breast cancer: The breast cancer subtype based on the ER status and HER2 status was available for 454 patients: 26.4% (120/454) were ER−/HER2−, 22.0% (100/454) ER−/HER2+, 37.4% (170/454) ER+/HER2−, and 14.1% (64/454) ER+/HER2+ (Table 1).