HER2 testing on core needle biopsy specimens from primary breast cancers: interobserver reproducibility and concordance with surgically resected specimens

Table 7 Correlation between consensus immunohistochemistry and FISH results for core needle biopsy and surgically resected specimens.

Core needle biopsy specimens
	Number of tumors (%)
	Total	HER2 gene amplification by FISH
		Positive	Equivocal*	Negative
HER2 IHC score
3+	21	20 (95)	0 (0)	1 (5)
2+	19	11 (58)	0 (0)	8 (42)
0 or 1+	60	2 (3)	0 (0)	58 (97)
Total	100	33 (33)	0 (0)	67 (67)
Surgically resected specimens
	Number of tumors (%)
	Total	HER2 gene amplification by FISH
		Positive	Equivocal*	Negative
HER2 IHC score
3+	10	10(100)	0 (0)	0 (0)
2+	7	3 (43)	0 (0)	4 (57)
0 or 1+	8	0 (0)	0 (0)	8 (100)
Total	25	13 (52)	0 (0)	12 (48)

*For three tumors, FISH judgment was equivocal by the first counts, but by the second counts, the judgments changed into positive (Table 3). FISH, fluorescence in situ hybridization

ISSN: 1471-2407