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. 2022 Dec;15(12):1573–1578. doi: 10.25122/jml-2022-0213

Table 1.

HER2 Testing by Validated IHC Assay.

Status Score Significance Reflex HER2 FISH
Positive 3+ Uniform intense membrane staining of >30% of invasive tumor cells No
Equivocal 2+ Complete membrane staining, nonuniform or weak in intensity in at least 10% of the cells or intense complete membrane staining in 30% or less of tumor cells Yes
Negative 1+ Weak or incomplete membrane staining in any proportion of tumor cells No
Negative 0 No staining No

IHC – indicates immunohistochemistry; FISH – fluorescence in situ hybridization [Dako. HercepTest™, Code K5204. Instruction for Use, (PD04086US_02/K520421-5)].