EGFR gene amplification is relatively common and associates with outcome in intestinal adenocarcinoma of the stomach, gastro-oesophageal junction and distal oesophagus

Table 3 EGFR and HER2 silver in situ hybridization in intestinal-type adenocarcinomas according to anatomical location

Gene copy number status	Distal oesophagus	GOJ/cardia	Corpus	Antrum/pylorus	Total	P value
Gene copy number status	N = 20 (%)	N = 63 (%)	N = 65 (%)	N = 72 (%)	N = 220 (%)	(χ ² test)^c
EGFR amplification^a
Yes	5 (16.1)	13 (41.9)	2 (6.5)	11 (35.5)	31 (100.0)	0.013^d
No	15 (7.9)	50 (26.5)	63 (33.3)	61 (32.3)	189 (100.0)
Total N of amplification (%)	5/20 (25.0)	13/63 (20.6)	2/65 (3.1)	11/72 (15.3)	31/220 (14.1)
HER2 amplification^a
Yes	5 (17.2)	9 (31.0)	9 (31.0)	6 (20.7)	29 (100.0)	NS
No	15 (7.9)	54 (28.3)	56 (29.3)	66 (34.6)	191 (100.0)
Total N of amplification (%)	5/20 (25.0)	9/63 (14.3)	9/65 (13.8)	6/72 (8.3)	29/220 (13.2)
EGFR and HER2 co-amplification^a
Yes	2 (25.0)	1 (12.5)	1 (12.5)	4 (50.0)	8 (100.0)	NS
No	18 (8.5)	62 (29.2)	64 (30.2)	68 (32.1)	212 (100.0)
Total N of co-amplification (%)	2/20 (10.0)	1/63 (1.6)	1/65 (1.5)	4/72 (5.6)	8/220 (3.6)
P value (Fisher’s exact test)^b	NS	NS	NS	0.004^d

IHC immunohistochemistry, GOJ gastro-oesophageal junction, GCN gene copy number, NS not significant
^aAmplification, GCN >10 for EGFR; GCN >6 for HER2
^bConcordant vs. discordant EGFR and HER2 amplification status
^cDistal oesophagus, GOJ and cardia vs. corpus
^dStatistically significant

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