ERBB2 and breast cancer: The median HER2/EIF2C1copy number ratio in HER2-amplified breast cancers (6.55, range 1.3–17.3) was significantly higher than in HER2-non-amplified breast cancers (1.05, range 0.6–3.6, p = 0.000 Mann–Whitney U test), as shown in Fig. 3.