HER2 and Breast Cancer |
HER2 and Breast Cancer |
HER2 (Human Epidermal Growth Factor 2), also known as ERBB2, is a transmembrane receptor protein [1]. It is part of a larger family of proteins called epidermal growth factors (EGFs) [1]. The proteins in the EGF family transduce signals related to cell growth by phosphorylating (or activating) downstream proteins [2].
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Fig. 1:The protein structure of HER2 (ERBB2).
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Fig. 2: HER2 overexpression leads to increased cell proliferation in breast cancer.
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HER2 status |
IHC staining score |
FISH result (HER2 copies per nucleus) |
FISH ratio (HER2 gene signals to chromosome 17 signals) |
Positive |
3+ (uniform, intense staining in >30% of invasive tumor cells) |
>6 |
>2.2 |
Inconclusive/equivocal |
2+ (nonuniform/weak but complete staining in ≥10% of invasive tumor cells) |
4.0-6 |
1.8-2.2 |
Negative |
1+/0 (no staining or weak, incomplete staining) |
<4.0 |
<1.8 |
Last updated: 5/07/21
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