Table 2. Comparison of ER status determined by microarray-based classifiers to the ER status based on conventional IHC method in 1846 samples from 10 published data sets.

Expression-based ER status	ESR1 based ER+	ESR1 based ER-	P value	23-gene signature based ER+	23-gene signature based ER-	P value
IHC ER+	93.0%	7.0%	<2.20E-16	90.9%	9.1%	<2.20E-16
IHC ER-	15.1%	84.9%	<2.20E-16	21.8%	78.2%	<2.20E-16
Overall concordance	90.7%			87.3%
Basal	7.2%	92.8%	<2.20E-16	3.9%	96.1%	<2.20E-16
Luminal A	99.8%	0.2%	<2.20E-16	98.6%	1.4%	<2.20E-16
Luminal B	99.4%	0.6%	<2.20E-16	96.3%	3.7%	<2.20E-16
Her2	36.3%	63.7%	<2.20E-16	48.7%	51.3%	<2.20E-16