Moreover, the following parameters were also selected for further evaluation upon the results of univariate analysis (see Supplementary Table E2): age at BC diagnosis ≥ 65 years (p = 0.007), Trastuzumab treatment (p < 0.001), initial N stage N0 (p = 0.027), initial higher G stage (p = 0.077), preoperative KPS < 90% (p = 0.026), preoperative seizure (p = 0.004), tumor necrosis in preoperative MRI (p = 0.037), preoperative leukocytosis (p = 0.073), negative HER2 RS in BM (p = 0.047) and adjuvant brain radiation (p = 0.012). This evidence concerns the gene ERBB2 and breast cancer.