HER2-positive breast cancers are morphologically poorly differentiated with a marked pleomorphism and a high proliferation rate (high grade cancers) (Figure 1a); they are prone to lymph node metastasis, tend to show a degree of resistance to certain chemotherapeutic agents [46], and have a higher rate of recurrence and distant metastasis, causing a high mortality rate [47]. This evidence concerns the gene ERBB2 and cancer.