Compared to HR−/HER2 + subtype, HR + /HER2 + breast cancer had a lower tumor grade (III-IV, 51.5% vs. 74.4%, P < 0.0001), a smaller tumor size (T0-1, 49.8% vs. 43.4%, P < 0.0001), a lower nodal involvement (N0, 60.0% vs. 55.0%, P < 0.0001), and a lower rate of de novo stage IV disease (M1, 6.3% vs. 8.0%, P < 0.0001). Here, ERBB2 is linked to breast cancer.