Trastuzumab is a type of drug known as a monoclonal antibody, a man-made version of a very specific immune system protein. It attaches to HER2 and can help slow the growth of cancers that are HER2 positive. Trastuzumab may also stimulate the immune system to more effectively attack the cancer.

Trastuzumab is injected into a vein (IV), usually once a week or at a larger dosage once every 3 weeks.

Trastuzumab is used as a part of adjuvant (or neoadjuvant) therapy for early stage HER2-positive cancers to reduce the risk of the cancer coming back. It is given first with chemo, then by itself to complete a year of treatment.

Trastuzumab is also used to treat HER2-positive advanced breast cancers that return after chemo or continue to grow during chemo. Often, trastuzumab is combined with chemo. . If the cancer gets worse while on trastuzumab and chemo, often the trastuzumab is continued and the chemo is changed.

Side Effects:

Compared with chemo drugs, the side effects of trastuzumab are relatively mild. These side effects are less common after the first dose. These occur rarely and may include:

  • fever and chills
  • weakness
  • nausea
  • vomiting
  • cough
  • diarrhea
  • headache


Risk Factor

A more serious potential side effect is heart damage that can lead to a problem called congestive heart failure. For most (but not all) people, this effect is temporary and improves when the drug is stopped. The risk of heart problems is higher when trastuzumab is given with chemo drugs that also cause heart damage such as doxorubicin (Adriamycin) or epirubicin (Ellence).

Because this drug can cause heart damage, your heart function will be checked before treatment with a test like an echocardiogram or a MUGA. It will be checked again every few months during treatment with trastuzumab.

Major symptoms of congestive heart failure are,

  • leg swelling
  • shortness of breath
  • severe¬†fatigue

People having these symptoms should call their doctor right away.


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Oncologists, Breast Surgeons are the specialists who deal with the breast cancer