Table 3 Comparison of IHC results for ER, PGR, and Her2 with respective RT2-Profiler RNA expression values and Oncotype DX singe gene scores.

From: Oncotype DX Breast Cancer recurrence score resists inter-assay reproducibility with RT2-Profiler Multiplex RT-PCR

patient

ER Score (GHI)

ER IHC [% pos. cells]

unrestricted Ct-value

PR Score (GHI)

PGR IHC [% pos. cells]

unrestricted Ct-value

Her2 Score (GHI)

Her2 IHC [% pos. cells]

unrestricted Ct-value

1

+

100

+

2

1

2

+

80

+

30

1

3

+

100

+

100

+

1

+

5

+

100

+

+

100

+

30

6

+

90

+

+

0

+

30

+

7

+

98

+

95

+

1

8

+

100

100

40

10

+

90

+

70

1

11

+

100

+

+

100

+

1

+

12

+

90

+

+

80

+

1

+

14

+

100

+

+

100

+

15

+

15

+

100

100

1

16

+

60

+

+

80

+

30

+

17

+

100

+

+

100

30

+

19

+

95

+

+

70

+

30

+

20

+

100

+

+

100

+

40

+

21

+

100

+

95

1

22

+

100

+

+

100

+

40

+

23

+

90

+

1

+

*

40

+

24

+

80

+

80

1

25

+

95

+

+

40

+

40

+

26

+

100

+

+

100

+

1

27

+

100

+

70

+

40

28

+

90

+

+

80

+

1

+

29

+

70

+

+

40

+

40

+

30

+

100

+

+

95

+

30

+

31

+

90

+

40

30

32

+

100

+

+

85

+

10

+

I

+

60

+

75

10

+

II

+

90

+

+

45

10

III

+

90

+

+

90

+

10

+

IV

+

90

+

+

60

+

30

+

  1. The Oncotype Dx scores shown in Table 2 were allocated according to the respective thresholds (ER: neg. < 6.5, pos. ≥ 6.5; PR: neg. < 5.5; pos. ≥ 5.5; Her2: neg. < 10.7, 10.7 ≤ equivocal < 11.5, pos. ≥ 11.5), whereas the RT2-Profiler Ct values were defined as positive if Ct ≤ 35 and as negative if Ct > 35. The table reveals that with one exception the Oncotype Dx defines all analyzed samples as ER positive and Her2 negative regardless of IHC. Regarding the comparison of IHC and RNA detection the Oncotype Dx shows a correlation of 37.5% and the RT2-Profiler assay of 71.9%. The inter-assay correlation based on IHC confirmation is about 72% for ER and PGR, and 40.6% for Her2.