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Home > Understanding Breast Cancer > Treatment > Trastuzumab (Herceptin)


Trastuzumab (Herceptin)


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The drug trastuzumab (Herceptin) has been used for many years to treat metastatic breast cancer. Now, it is also used to treat 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/neu+) breast cancer). The HER2/neu protein is important for cancer cell growth. Trastuzumab is a specially made antibody that targets HER2/neu+ cancer cells. When attached to the HER2/neu protein, trastuzumab can slow or stop the growth of the 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/neu+ [83-84]. 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/neu+ cancers [85-88].  

Trastuzumab is only used to treat HER2/neu+ cancers and has no role in the treatment of HER2/neu-negative (HER2/neu-) 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 [86-88]. This risk of heart problems may be higher with chemotherapy regimens containing an anthracycline than with regimens without an anthracycline [88]. 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 [80].

Because of the risk of heart problems, trastuzumab is most often 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 therapy. 

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


For more information on trastuzumab, visit the National Comprehensive Cancer Network (NCCN) or the American Society for Clinical Oncology (ASCO).

Updated 03/28/14

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