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    Research Fast Facts: HER2-Positive Breast Cancer
    Fact Sheet

    The drug trastuzumab (Herceptin) is used to treat metastatic breast cancer and early breast cancer (including lymph node-positive and some lymph node-negative cancers).

    How does trastuzumab work?

    Some breast cancers have high amounts of a protein called HER2/neu on the surface of the cancer cells (called HER2/neu-positive (HER2-positive) breast cancer). The HER2/neu protein is important for cancer cell growth.  

    Trastuzumab is a specially made antibody that targets HER2-positive cancer cells. When attached to the HER2/neu protein, trastuzumab can slow or stop the growth of these cancer cells.

    Testing for HER2/neu status

    The HER2/neu status of a tumor is determined by testing tissue removed during a biopsy. All newly diagnosed breast cancers are tested for HER2/neu status.  

    About 15 to 20 percent of breast cancers are HER2-positive [78-79]. These breast cancers can be treated with trastuzumab.  

    Learn more about HER2/neu status.

    Trastuzumab for the treatment of HER2/neu-positive breast cancer

    Studies show chemotherapy plus trastuzumab cuts the risk of breast cancer recurrence in half compared to chemotherapy alone among women with HER2-positive cancers [80-83].  

    Trastuzumab is only used to treat HER2-positive cancers and has no role in the treatment of HER2/neu-negative cancers.  


    For a summary of research studies on trastuzumab and overall survival in early breast cancer, visit the Breast Cancer Research section.

    Risks related to trastuzumab

    Trastuzumab use is linked to congestive heart failure, a serious heart condition. In clinical trials, about two to three percent of those treated with chemotherapy plus trastuzumab had heart failure, compared to fewer than one percent of those treated with chemotherapy alone [81-83]. This risk of heart problems may be higher with chemotherapy regimens containing an anthracycline than with regimens without an anthracycline [83]. For most people who develop a heart problem while taking trastuzumab, the condition improves after stopping trastuzumab. For a few people, however, the heart problem may be permanent.

    Your heart will be checked before and during treatment with trastuzumab to help ensure there are no problems. To help protect the heart while taking trastuzumab, it may be helpful to adopt a lifestyle that includes a healthy diet, regular exercise and for those who smoke, quitting smoking [76].

    Because of the risk of heart problems, trastuzumab is usually only recommended for people with breast tumors that are larger than one centimeter. There is controversy as to whether very small (smaller than one centimeter), lymph node-negative tumors should be treated with trastuzumab.  

    To learn more about trastuzumab, visit the National Institutes of Health’s Medline Plus website.

     Komen Support Resources  

    • Our breast care helpline 1-877 GO KOMEN (1-877-465-6636) provides free, professional support services and help finding local support groups and resources. Our trained and caring staff are available to you and your family Monday through Friday from 9:00 a.m. to 10:00 p.m. ET and from 6:00 a.m. to 7:00 p.m. PT.

    • Our Message Boards offer online forums for breast cancer survivors, including a forum on targeted therapies, to share their experiences and advice with other breast cancer survivors. 
    • Our fact sheets, booklets and other education materials offer additional information for survivors.  

    Updated 04/30/14


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