Compared with other subtypes, HER2-positive patients with BMs were slightly younger at the time of breast cancer (median of 52 years for HER2 positive versus 53.0 for HER2 negative; P < 0.001) and BM diagnosis (median age 56 years for HER2-positive versus 58 for HER2-negative; P = 0.009). Here, ERBB2 is linked to breast cancer.