Trastuzumab (Herceptin)

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Trastuzumab (Herceptin)


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Trastuzumab (Herceptin) is given as a shot into a vein (intravenously).

How It Works

Trastuzumab targets breast cancer cells that make too much of (overexpress) a protein called HER-2, which is found on the surface of some cancer cells. Trastuzumab slows or stops the growth of these cells. Not all breast cancers make this protein.

Trastuzumab is used after surgery and chemotherapy to treat breast cancer that tests positive for HER-2. It is also used to treat metastatic or recurrent HER-2 breast cancer. It may be used by itself or may be combined with other medicines.

Why It Is Used

Trastuzumab slows or stops the growth of breast cancer that overexpresses the HER–2 protein. It is used only to treat this type of breast cancer. As many as 1 in 4 breast cancers overexpress HER-2.4 These cancers tend to grow faster and are more likely to come back (recur) than breast cancer that does not overproduce HER-2.2

Trastuzumab is used for women who have HER-2 breast cancer. It is used to stop the cancer from coming back, and to control breast cancer that has spread (metastatic).

How Well It Works

After HER-2 breast cancer is first treated, trastuzumab treatment lowers the risk of the cancer coming back (recurring). Taking trastuzumab after surgery and chemotherapy makes it more likely that a woman will stay cancer-free and live longer. This is based on studies that have lasted up to 3 years after initial treatment.4, 3, 1

Trastuzumab is also used to treat HER-2-positive cancer that has recurred or spread (metastasized). It slows HER-2 tumour growth and reduces tumour size.

Side Effects

Fever and chills commonly occur during the first treatment with trastuzumab and become less severe with later treatments. Other possible serious side effects can include difficulty breathing and heart failure.

Less serious side effects may include:

  • Diarrhea.
  • Headache.
  • Nausea or vomiting.
  • Pain.
  • Skin rash.
  • Weakness.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Trastuzumab can cause heart failure if it damages the heart muscle. You will be carefully evaluated for heart disease before and during treatment with this medicine.

Trastuzumab is a powerful treatment for HER-2 breast cancer. The heart risk linked to trastuzumab can also be serious. Talk to your doctor about whether trastuzumab is a good choice for you.

Trastuzumab can cause birth defects. Do not use this medicine if you are pregnant or trying to become pregnant.

Trastuzumab should be given only under the supervision of a medical oncologist.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Smith I, et al. (2007). Two-year follow-up of trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer: A randomized controlled trial. Lancet, 369(9555): 29–36.
  2. Shapiro CL (2003). Metastatic breast cancer. In B Furie et al., eds., Clinical Hematology and Oncology, pp. 750–762. Philadelphia: Churchill Livingstone.
  3. Romond EH, et al. (2005). Trastuzumab plus adjuvant chemotherapy for operable HER2-positive breast cancer. New England Journal of Medicine, 353(16): 1673–1684.
  4. Piccart-Gebhart MJ, et al. (2005). Trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer. New England Journal of Medicine, 353(16): 1659–1672.


By Healthwise Staff
Primary Medical Reviewer Joy Melnikow, MD, MPH - Family Medicine
Specialist Medical Reviewer Douglas A. Stewart, MD - Medical Oncology
Last Revised October 26, 2009

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.