HER2 Tumor Marker Test
The HER2 tumor marker test is a diagnostic tool used to determine if a person's cancer cells have an overexpression or amplification of the human epidermal growth factor receptor 2 (HER2) protein.
What is HER2?
HER2 is a gene that helps control cell growth, division, and repair. In some cases of cancer, particularly breast and ovarian cancer, the HER2 gene can become altered, leading to an overproduction of the HER2 protein on the surface of cancer cells.
Purpose of the Test
The primary purpose of the HER2 tumor marker test is to identify patients with cancers that may benefit from targeted therapies, such as trastuzumab (Herceptin), which specifically target the HER2 protein.
Types of HER2 Tests
There are two main types of HER2 tests:
- Immunohistochemistry (IHC) test: This test measures the level of HER2 protein on the surface of cancer cells.
- Fluorescence in situ hybridization (FISH) test: This test measures the number of copies of the HER2 gene in cancer cells.
How the Test is Performed
A sample of tissue from the tumor is removed during a biopsy or surgery and sent to a laboratory for analysis. The tissue sample is then examined using either IHC or FISH techniques to determine the level of HER2 protein or gene amplification.
Interpretation of Results
The results of the HER2 test are typically reported as:
- HER2-positive: The cancer cells have an overexpression or amplification of the HER2 protein, and targeted therapies may be effective.
- HER2-negative: The cancer cells do not have an overexpression or amplification of the HER2 protein, and targeted therapies may not be effective.
- Borderline or equivocal results: The results are unclear, and additional testing may be necessary to determine the HER2 status.
Clinical Significance
The HER2 tumor marker test has significant implications for the diagnosis, treatment, and prognosis of certain types of cancer. Patients with HER2-positive cancers may benefit from targeted therapies, which can improve treatment outcomes and survival rates.
Article last updated on: 15th June 2025.
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