What Is HER2 Status and How Does It Relate to Breast Cancer?

HER2 gene
HER2 Gene. Protein Data Bank

HER2, which is also called HER2/neu and HER-2, is the acronym for human epidermal growth factor receptor 2. Knowing your HER2 status is an important part of your diagnosis.

What Is HER2?

HER2 is a gene that sends control signals to your cells, telling them to grow, divide, and make repairs. A healthy breast cell has 2 copies of the HER2 gene. Some kinds of breast cancer get started when a breast cell has more than 2 copies of that gene, and those copies start over-producing the HER2 protein.

As a result, the affected cells grow and divide much too quickly.

Is HER2 Inherited?

This genetic problem is not inherited from your parents. The most likely cause of this problem is aging, and wear and tear on the body. It is not yet known if environmental factors (pollution, smoke, fumes) are part of the cause of this problem.

Positive vs. Negative Test Results

If your breast cancer is tested for HER2 status, the results will be graded as positive or negative. If your results are graded as HER2 positive, that means that your HER2 genes are over-producing the HER2 protein and that those cells are growing rapidly and creating cancer. If your results are graded HER2 negative, then the HER2 protein is not causing cancer.

Available Treatments

Herceptin (trastuzumab) is a drug which is currently being used to treat HER2 positive breast cancer. It is a targeted therapy and is also referred to as an immune treatment.

This drug will be given intravenously, once every 2-3 weeks. Once it is in your system, Herceptin targets the HER2 protein production. This helps to stop the growth of the HER2 positive cancer cells.

What Can Herceptin Do?

Some results of Herceptin treatment include:

  • shrinks HER2 positive tumors, before surgery
  • gets rid of HER2 positive cancer cells that have spread beyond the original tumor
  • helps prevent recurrence (return) of the HER2 positive cancer if it was a 2 cm. or larger tumor, or if cancer had spread to the lymph nodes.

Tests for HER2

Your doctor may call for a few tests:

  • IHC: ImmunoHistoChemistry—this test measures the production of the HER2 protein by the tumor. The test results are ranked as 0, 1+, 2+, or 3+. If the results are 3+, your cancer is HER2-positive.
  • FISH: Fluorescence In Situ Hybridization—this test uses fluorescent probes to look at the number of HER2 gene copies in a tumor cell. If there are more than 2 copies of the HER2 gene, then the cancer is HER2 positive.

The Bottom Line

HER2 positive breast cancer is diagnosed by the IHC or FISH test. A result of HER 2 positive is important, as it indicates that cancer can be treated with Herceptin, as well as Perjeta and Kadcyla. If your cancer is diagnosed as HER2 positive, it is most likely aggressive. Starting treatment as soon as possible will help improve your survival, as well as help to prevent recurrence.

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