ERBB2 and breast cancer: Among the five intrinsic BC subtypes, non-luminal HER2-positive tumors had the highest total recurrence rate (52.3%, 11 of 21), followed by HER2-positive luminal B tumors (42.5%, 17 of 40), luminal B tumors (33.6%, 35 of 104), and basal tumors (32%, 8 of 25).