ERBB2 and neoplasm: A study based on the SEER database from 2010 to 2014 revealed that age < 35 y/o (3.6% vs. 1.3%), tumor > 2.0 cm (48.8% vs. 36.8%), stage III/IV (21.5% vs. 13.7%), tumor grade III (47.9% vs. 17.4%), and less PR expression (72.9% vs. 87.7%) was more common in the HR+ /HER2+ subgroup compared to HR+ /HER2– patients [18].