HER2 Testing Characteristics Can Predict Residual Cancer Burden following Neoadjuvant Chemotherapy in HER2-Positive Breast Cancer
Table 3
HER2 characteristics of HER2+ cases receiving neoadjuvant chemotherapy.
Total
RCB-0 ()
RCB-I ()
RCB-II ()
RCB-III ()
values‡
Mean (SE)
Mean
SE
Mean
SE
Mean
SE
Mean
SE
%
%
%
%
<0.0001§
IHC category
IHC 3+ 100%
102
51
81.0%
27
87.1%
22
47.8%
2
25.0%
IHC 3+ <100%
24
8
12.7%
2
6.5%
11
23.9%
3
37.5%
IHC 2+
22
4
6.3%
2
6.5%
13
28.3%
3
37.5%
<0.0001§
HER2 copies
19.7 (10.5)
22.5
8.8
22.6
9.8
15.5
11.5
9.8
6.3
0.0015§
HER2/CEP17 ratio
7.5 (5.9)
8.5
6.2
8.3
4.8
6.1
6
4.5
5.1
Na
FISH groups: HER2/CEP17 ratio; mean HER2 copies
Group 1: ≥2.0; ≥4.0
134
60
93.8%
31
96.9%
38
80.9%
5
62.5%
Subset 1A: ≥2.0; ≥4.0 to <6.0
9
1
1.6%
1
3.1%
7
14.9%
0
0.0%
Subset 1B: ≥2.0; ≥6.0
125
59
92.2%
30
93.8%
31
66.0%
5
62.5%
Group 2: ≥2.0; <4.0
1
0
0.0%
1
3.1%
0
0.0%
0
0.0%
Group 3: <2.0; ≥6.0
7
2
3.1%
0
0.0%
3
6.4%
2
25.0%
Group 4: <2.0; ≥4.0 to <6.0†
7
2
3.1%
0
0.0%
5
10.6%
0
0.0%
Group 5: <2.0; <4.0†
2
0
0.0%
0
0.0%
1
2.1%
1
12.5%
Not including two patients with IHC 0 and one IHC 3+ patient who does not have staining percent. †One RCB-II case with heterogeneity. ‡Continuous variable values are calculated using the Kruskal-Wallis test, and values for the categorical variables are calculated using the Chi square or Fisher’s exact test. §Statistically significant.
