ERBB2 and neoplasm: HER2 positivity is confirmed based on the score of 3+ in ≥10% of tumor cells in the immunohistochemistry (IHC) test or a HER2/chromosome enumeration probe (CEP17) ratio of ≥2 in the in-situ hybridization (ISH) assay along with an average HER2 copy of <4 signals per cell in the pathological test [6,7].