Table 2.

Correlation between HER2 protein expression and HER2 gene amplification

HER2 Dual ISH and FISH	Immunohistochemistry for HER2
	3 + (n = 28)	2 + (n = 23)	1 + (n = 9)	0 (n = 148)	Total
Amplified	27	6	0	0	33
Not-amplified	1	17	9	148	175

HER2, human epidermal growth factor receptor 2; ISH, in situ hybridization; FISH, fluorescence in situ hybridization.