ERBB2 and breast neoplasm: In addition, patients with breast tumors with high HER2 mRNA expression levels have a 26% reduced survival compared to patients with breast tumors with low/intermediate HER2 expression levels (126.37 ± 3.1 months for low/intermediate expression versus 99.96 ± 6.6 months for high HER2-expressing tumors) (Figure 3A).