HER2 Testing Characteristics Can Predict Residual Cancer Burden following Neoadjuvant Chemotherapy in HER2-Positive Breast Cancer

Table 1

ASCO/CAP guidelines categorize HER2 FISH results into 5 groups based on HER2/CEP17 ratio and average HER2 copy number.

Group	HER2/CEP17 ratio	Average HER2 copy number
1	≥2.0	≥4.0
2	≥2.0	<4.0
3	<2.0	≥6.0
4	<2.0	≥4.0 and <6.0
5	<2.0	<4.0