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Breast Cancer (cont.)

What Is HER2-Positive Breast Cancer?

HER2- positive breast cancer is any breast cancer that expresses the HER2 protein (sometimes referred to as HER2/neu), a protein responsible for cancer cell growth. About 15%-25% of breast cancers are HER2-positive. Because the treatment for HER2-positive breast cancers is different, all breast cancer tissue is tested for the presence of HER2. This is done on the surgically removed tissue sample, which is tested for hormone receptor status (estrogen and progesterone receptors), as well.

What Tests Assess HER2?

There are two approved tissue testing methods for HER2 status. In 2013, the American Society of Clinical Oncologists (ASCO) and the College of American Pathologists (CAP) issued an updated joint clinical practice guideline about HER2 testing for breast cancer. The two approved methods currently used in the U.S. to test for HER2 are immunohistochemistry (IHC) and in-situ hybridization (ISH). IHC testing uses specially labeled antibodies to show how much of the HER2 protein is present on the cancer cell surface, while ISH testing measures the number of copies of the HER2 gene inside each cell. There are two main types of ISH tests: fluorescence and bright-field ISH. Fluorescence in situ hybridization is referred to as FISH. Both of these tests are performed on the tumor sample that is removed at the time of surgery.

Are HER2-Positive Breast Cancer Symptoms and Signs Different Than Those of HER2-Negative Breast Cancer?

Signs and symptoms of HER2-positive breast cancer are the same as those of all breast cancers. It is not possible to determine HER2 presence by the clinical signs and symptoms.

What Is the Treatment for HER2-Positive Breast Cancer?

Specialized treatments, known as targeted therapies, have been developed to treat breast cancers that express the HER2 protein. Targeted therapies are newer forms of cancer treatment that specifically attack cancer cells and do less damage to normal cells than traditional chemotherapy. Targeted therapies for HER2-positive breast cancer include the following:

  • Trastuzumab (Herceptin) is an antibody against the HER2 protein Adding treatment with trastuzumab to chemotherapy given after surgery has been shown to lower the recurrence rate and death rate in women with HER2-positive early breast cancers. Using trastuzumab along with chemotherapy has become a standard adjuvant treatment for these women.
  • Pertuzumab (Perjeta) also works against HER2-positive breast cancers by blocking the cancer cells' ability to receive growth signals from HER2.
  • Lapatinib (Tykerb) is another drug that targets the HER2 protein and may be given combined with chemotherapy. It is used in women with HER2-positive breast cancer that is no longer helped by chemotherapy and trastuzumab.
  • T-DM1 or ado-trastuzumab emtansine (Kadcyla) is a combination of Herceptin and the chemotherapy medication emtansine. Kadcyla was designed to deliver emtansine to cancer cells by attaching it to Herceptin.
Medically Reviewed by a Doctor on 11/20/2017

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