Table 2. Clinicopathologic characteristics of HER2-positive primary breast cancers with EGFR overexpression or high EGFR copy number in the first set.

	EGFR overexpression (3+)			EGFR overexpression (2+ or more)			High EGFR copy number
Clinicopathological characteristics	Absent (n=209)	Present (n=28)	P-value	Absent (n=179)	Present (n=58)	P-value	Absent (n=208)	Present (n=24)	P-value
pT stage			0.070			0.130			0.830
T1	99 (47.4)	8 (28.6)		86 (48.0)	21 (36.2)		95 (45.7)	10 (41.7)
T2–T4	110 (52.6)	20 (71.4)		93 (52.0)	37 (63.8)		113 (54.3)	14 (58.3)
pN stage			0.322			0.230			1.000
N0	111 (53.1)	12 (42.9)		97 (54.2)	26 (44.8)		108 (51.9)	13 (54.2)
N1–N3	98 (46.9)	16 (57.1)		82 (45.8)	32 (55.2)		100 (48.1)	11 (45.8)
Stage			0.356			0.119			1.000
I and II	159 (76.1)	19 (67.9)		139 (77.7)	39 (67.2)		158 (76.0)	18 (75.0)
III	50 (23.9)	9 (32.1)		40 (22.3)	19 (32.8)		50 (24.0)	6 (25.0)
Histologic grade			0.385			0.067			0.234
I and II	63 (30.1)	6 (21.4)		58 (32.4)	11 (19.0)		62 (29.8)	4 (16.7)
III	146 (69.9)	22 (78.6)		121 (67.6)	47 (81.0)		146 (70.2)	20 (83.3)
Lymphovascular invasion			0.838			0.282			1.000
Negative	126 (60.3)	16 (57.1)		111 (62.0)	31 (53.4)		126 (60.6)	15 (62.5)
Positive	83 (39.7)	12 (42.9)		68 (38.0)	27 (46.6)		82 (39.4)	9 (37.5)
Hormone receptor			<0.001			<0.001			0.078
Negative	123 (58.9)	26 (92.9)		94 (52.5)	55 (94.8)		125 (60.1)	19 (79.2)
Positive	86 (41.1)	2 (7.1)		85 (47.5)	3 (5.2)		83 (39.9)	5 (20.8)
p53 overexpression			0.227			0.098			0.130
Negative	117 (56.0)	12 (42.9)		103 (57.5)	26 (44.8)		115 (55.3)	9 (37.5)
Positive	92 (44.0)	16 (57.1)		76 (42.5)	32 (55.2)		93 (44.7)	15 (62.5)
Ki-67 index			0.014			0.003			0.879
	25.1±14.3	32.3±15.1		24.4±13.3	30.8±17.1		26.1±14.2	26.6±16.9

Abbreviations: EGFR=epidermal growth factor receptor; HER2=human epidermal growth factor receptor 2.