If present in high amounts, HER2 prompts cancer cells to grow andmetastasize(spread) more quickly.
Knowing your HER2 status helps determine which cancer treatments may be most effective for you.
This article describes why and when HER2 testing is done.
Verywell / Brianna Gilmartin
What Is the Purpose of HER2 Testing?
HER2 proteins are found on the surface of breast cells, whether cancerous or normal.
TheHER2gene is the gene that carries instructions on how to make these proteins.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
Each breast cell contains two copies of theHER2gene.
While normal breast cells have HER2 receptors, HER2-positive breast cancer cells have up to 100 times more.
HER2 receptors function as the attachment points for substances called growth factors (GH) that promote cellular growth.
Knowing your HER2 status helps you make informed choices about your available treatments.
If you have HER2 receptors, these drugs will target and lock onto them.
These include such options as:
The types ofchemotherapyused can also vary based on your HER2 status.
Risk of a HER2-Positive Result
Roughly 25% of people with breast cancer areHER2-positive.
In the past, a HER2-positive status was associated with a poor prognosis.
However, with the advent of targeted therapies, the prognosis of HER2-positive breast cancer is favorable to excellent.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
FISH is more accurate and may be used when IHC results aren’t definitive.
Because of this, a HER2-positive tumor may be misdiagnosed and only become detectable when the tumor is larger.
This is why retesting is done if breast cancer recurs or progresses to stage 4.
This describes the percentage of treated people who live forat leastfive years after their diagnosis.
Five-year survival rates for people with HER2-positive breast cancer are greatly influenced by theirhormone receptor status.
Testing positive means that you are sensitive to targeted drugs specifically designed for HER2-positive breast cancer.
Gutierrez C, Schiff R.HER2: biology, detection, and clinical implications.Arch Pathol Lab Med.
2011;135(1):55-62. doi:10.1043/2010-0454-RAR.1
American Cancer Society.Breast cancer HER2 status.
2015;68(2):93-9. doi:10.1136/jclinpath-2014-202571
National Cancer Institute.Cancer stat facts: female breast cancer subtypes.
2018;36(20):2105-2122. doi:10.1200/JCO.2018.77.8738
