Other than skin cancer, breast cancer is the most common cancer in people assigned female at birth. In fact, it makes up
Some breast cancers are HER2-positive. This means that the cancer cells have high levels of HER2 protein (human epidermal growth factor receptor 2) on their surface, which helps them grow faster. From 2012 to 2016,
If you have been diagnosed with breast cancer, an IHC test can tell you if it is HER2 positive. This test is used when and how it is done.
In an IHC test, antibodies that are specific to the HER2 protein are added to the tissue sample. If HER2 is present on the cells, these antibodies will stick to it.
A color change will be seen in areas where HER2 is present when a special chemical is added to the sample. When reporting your results, the magnitude of the color change is used.
The amount of HER2 on the surface of cells collected through a surgery is determined by the Ihc test.
Your doctor will also use the results from a biopsy or surgery to determine the clinical stage of the cancer. Staging for breast cancer also takes into account certain markers on the surface of cancer cells. These include hormone receptors and HER2.
When you’ve been diagnosed with breast cancer, it’s important to know the stage of your cancer, as well as your hormone receptor status and your HER2 status. This information helps determine the type of treatment you receive.
IHC testing is usually done on a sample of breast tissue that’s been collected through a biopsy. An IHC test can also be performed on tissue that’s been removed from a surgery, for example from a mastectomy or a lumpectomy.
Doctors use a thin, hollow needle to guide a tissue sample to be removed from a patient.
Prior to collecting the sample, you’ll be given an injection of a local anesthetic to numb the area where the needle will be inserted. While you may feel some pressure or discomfort during the procedure, you shouldn’t feel pain.
When a breast biopsy is over, you go home. The sample will be sent to a Pathologist. A doctor is a Pathologist.
When the testing on your biopsy sample is complete, your doctor will contact you with the results. This typically happens a few days to a week after your biopsy.
The results of an IHC test are reported in three parts.
|0 or 1+||Your cancer is considered HER2-negative.|
|2+||The HER2 status of your cancer is considered to be equivocal. Additional testing will be needed to more firmly determine its HER2 status.|
|3+||Your cancer is considered HER2-positive.|
If you receive a result of 2+ (equivocal), a fluorescence in situ hybridization (FISH) test is typically done as a follow-up.
FISH testing is generally considered to be more accurate than an IHC test. This is because IHC tests look for the amount of HER2 protein on the cell surface, while FISH tests look at the number of copies of HER2 genes in the cell.
IHC testing is often done first because it takes longer to get results, and FISH tests are more expensive.
A FISH test uses a piece of DNA that has a fluorescent molecule attached. This piece of DNA can bind to the HER2 gene, HER2/neu, present inside of cells in the biopsy sample.
After the DNA piece has bound to HER2/neu, the attached fluorescent molecule allows a pathologist to count any extra copies of the gene under a microscope. The presence of extra copies of HER2/neu indicates HER2-positive cancer.
The magnitude of the color change in the tissue sample is what determines the results of an IHC test. Each lab or pathologist has their own way of interpreting these changes.
Some tumors can also have a combination of cells that are HER2-positive and others that are HER2-negative, complicating the interpretation of IHC results. This is
If the results are equivocal, it is possible for an IHC test to be inaccurate. This is one of the reasons that FISH testing is used.
If you receive an inaccurate IHC result, you may have to change your breast cancer treatment.
- A false-negative result can mean that your doctor likely won’t prescribe targeted therapy drugs directed at HER2, which can greatly benefit people with HER2-positive breast cancer.
- A false-positive result can mean that you may receive targeted therapy drugs that aren’t effective for your breast cancer. You may also experience unnecessary side effects from these treatments.
If you are concerned about the results of your IHC test, you should ask your doctor to do a FISH test as well.
According to a 2020 report, the cost of an IHC test for breast cancer was $127 to $129 per sample. This may also vary according to factors like your healthcare team, your location, and the lab analyzing the sample.
These costs don’t include the cost of the biopsy or surgery that’s done to collect the sample used for an IHC test. However, most insurance providers will cover tests that are medically necessary for the diagnosis or treatment of a health condition, such as breast cancer.
“If you don’t know what’s covered, contact your insurance provider.”
If your breast cancer is HER2 positive, you can use an IHC test. The results can have a big impact on the type of treatment that is recommended.
IHC testing uses specific HER2 antibodies to find out if a breast is HER2 positive. A color change will happen if a special chemical is added to the sample.
It is possible for IHC tests to be incorrect. A FISH test is used when there is concern about the results of an IHC test. It may take longer to get your results, but this test is more accurate.