In contrast, in a meta-analysis on 6629 women with breast cancers, 9% with a 3+ IHC score (HER2 overexpression) were not amplified using ISH, and 4% with a 0/1+ IHC score (HER2 low expression) had a high copy number of the HER2 gene [28]. This evidence concerns the gene ERBB2 and breast carcinoma.