In HER2 protein (synonyms: Her2 protein; cerbB 2, Her 2/neu; HER-2; human epidermal growth factor receptor; human epidermal growth factor receptor-2/neuroblastoma) is a membrane-bound receptor that belongs to the tyrosine kinase receptors. It is found on the surface of somatic cells and tumor cells. This receptor belongs to the epidermal growth factor receptors.
HER2 protein:
- Is encoded by the c-erb2 gene (cellular avian erythroblastosis homologue B2).
- Stimulates cell proliferation and inhibits apoptosis (programmed cell death).
HER2 protein plays an important role in the diagnosis and treatment of breast carcinoma (breast cancer). In up to 20% of cases, this receptor is strongly overexpressed (i.e. increased protein biosynthesis – production of a protein – which can lead to an increased concentration of this protein in the cell; this overexpression can be caused by faulty gene regulation). Overexpression is associated with a poorer prognosis (serum HER2 protein levels correlate with progression-free survival with therapy as well as overall survival)
A simple procedure is immunohistochemical processing of a biopsy (tissue sample) to detect HER2 protein. To do this, the sample is coated with an antibody against the protein.
The procedure
Material needed
- Biopsy (tissue sample) or serum (approx. 1ml); mailing possible, sample transport preferably refrigerated (+ 2°C – + 8°C).
Preparation of the patient
- Not necessary
Disruptive factors
- Not known
Normal value (biopsy/tissue sample)
| Response scale | Statement |
| 0 | negative no overexpression |
| 1+ | weak response no overexpression |
| 2+ | moderately strong response weak overexpression |
| 3+ | strong response strong overexpression |
Indications
- Mammary carcinoma (breast cancer)
- Therapy control/monitoring and prognosis assessment in breast carcinoma.
- Lack of tumor tissue status for HER2 protein expression.
Interpretation
Interpretation of increased values
- Her-2 receptor positive breast carcinoma.
Important Notes.
- In the course of a metastatic process (formation of daughter tumors) of breast carcinoma, there is a possibility of clonal selection of HER2 protein-positive cells, i.e.an initially HER2 protein-negative tumor may overexpress HER2 protein in its metastases. Therefore, serum analysis of HER2 protein is recommended even in the case of initially negative HER2 protein status of the primary tumor (first tumor) in the tissue examination in the further follow-up (follow-up).
- HER2 protein is also useful in patients with localized primary tumor for prognosis assessment. If the HER2 protein status of the primary tumor is not raised in the tissue examination, serum determination – if positive failure can indicate overexpression of HER2 protein – and thus provide valuable assistance in the selection of therapeutic options.
- Benign disease of the mammary gland (breast) rarely results in elevation of HER2 protein serum levels (caution: massive liver dysfunction). If HER2 protein serum levels above 14 μg/l occur, further workup is always required.