Too much HER2 protein, however, can cause some types of breast cancer to grow and spread.
HER2-positive breast cancers have abnormally high levels of HER2 receptors, whereas HER2-negative breast cancers dont.
Get our printable guide for your next healthcare provider’s appointment to help you ask the right questions.
Get our printable guide for your next healthcare provider’s appointment to help you ask the right questions.
These proteins are related to the genetic material of cancer cells.
For example, withestrogen receptor-positivebreast cancer, estrogen binds to specific receptors on breast cancer cells, stimulating proliferation.
It’s important to note, however, thatallbreast cellsboth cancerous and noncanceroushave HER2 receptors on their surfaces.
Verywell / Brianna Gilmartin
In positive cases, the abundance of receptors fuels the cancer.
How HER2-Positive Cancers Behave
HER2-positive tumors can behave differently in a number of ways.
HER2-positive breast cancers account for 30% of all breast cancers.
HER2-positive tumors are more likely to have a tumor grade of 3.
Treatment withHerceptin (trastuzumab)can cut this risk by half.
The pattern of breast cancer recurrence may also differ.
The risk of metastases may also depend on associated factors.
For example, the risk ofliver metastases from breast canceris higher with HER2-positive tumors if people also smoke.
Who’s at Risk?
Some people are more likely than others to have HER2-positive breast cancer.
What they found was that:
Determining Your HER2 Status
Abreast biopsyis used to determine HER2 status.
The biopsy can be sent for laboratory testing with an immunohistochemistry test.
The fluorescence in situ hybridization test looks for the HER2 gene in breast cancer cells.
The results of animmunohistochemistrytest show different levels of HER2 positivity.
For example, a tumor may be reported as 0, 1+, 2+, or 3+.
Tumors with a higher number may be referred to as having anoverexpression of HER2.
The impact of being HER2-positive on breast cancer survival is, of course, a top concern.
The results you receive will depend on which section of the tumor was sampled in a biopsy.
Status Changes
It’s also important to know that HER2 status canchange.
A tumor that is initially HER2-positive may become HER2 negative if it recurs or spreads.
Likewise, a tumor which is initially HER2 negative may become HER2-positive if it recurs.
HER2 status should always be retested following a recurrence.
People with HER2-positive tumors are less likely to respond tobreast cancer chemotherapythan those who are negative.
Does HER2-negative need chemotherapy?
There are also differences in the best treatments for HER2-negative cancers and thetreatments for metastatic HER2-positive tumors.
As with early-stage tumors, HER2-targeted therapies often improve survival, whereas anti-estrogen therapies are often ineffective.
These tumors may also respond differently to treatments ranging from chemotherapy toimmunotherapy drugs.
What foods should I avoid if I’m HER2-positive?
HER2 status can change, so retesting after a recurrence is often recommended.
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