Table 3.

Clinicopathological characteristics and discrepant HER2 FISH status between primary tumour and distant metastasis

Case no.	Age (years)	Clinicopathological characteristics				HER2 status
		Tumour size (cm)	Histology	Gradea	Metastatic	Metastases	Primary tumour	Explanationb
1	34	1.0	Ductal	3	Pleura	Amplified	Negative	True discrepancy
2	52	Not available	Ductal	3	Cerebrospinal fluid	Amplified	Negative	True discrepancy
3	65	2.5	Ductal	3	Pleura	Amplified	Negative	True amplification
4	52	1.6	Ductal	3	Pleura	Negative	Amplified	True amplification
5	47	1.8	Ductal	3	Ascites	Negative	Amplified	Borderline
6	47	Not available	Ductal	3	Pleura	Negative	Amplified	True amplification
7	82	5.2	Ductal	2	Pleura	Negative	Amplified	Borderline
8	62	2.5	Ductal	3	Lung	Negative	Amplified	True negative

HER2, gene encoding human EGF-like receptor 2; FISH, fluorescence in situ hybridization; true discrepancy, discrepancy remained unexplained; true amplification, amplification was found both in the metastasis and in the primary tumour after review; true negative, amplification was not confirmed after review; borderline, discrepancy was explained by interpretational difficulty due to a HER2/CEP17 ratio close to the threshold of 2 or less. ^aNuclear grade (1 to 3); ^bexplanations for the discrepancies of HER2 status.