Table 3.

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;