As compared to HER2 IHC 0/1+ BCs, HER2 IHC 2+/ISH-negative BCs are significantly associated with a larger tumor size, positive lymph node status, higher histological grade, and an increased Ki-67 index; compared with HER2 IHC 0 tumors, the HER2-low BCs exhibit a lower histological grade [90,97]. This evidence concerns the gene ERBB2 and neoplasm.