- HER2 status must be known. (Positive = 3+ over-expression by IHC in > 30% of invasive tumour cells OR HER2 gene amplification by FISH/CISH > 6 HER2 gene copies per nucleus, OR a FISH/CISH ratio: HER2 gene copies to chromosome 17 signals of ≥ 2.2. All other results will be considered negative).