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Targeted therapy

Targeted therapy uses specific drugs that are known to target the specific proteins or enzymes that play a role in the growth of cancer cells.  

Targeted treatments such as trastuzumab to treat HER2-positive breast cancer and the hormone-blocking therapies (tamoxifen, anastrozole, letrozole, exemestane) for hormone-receptor positive breast cancer are examples of common targeted treatments available in Australia. Read more about hormone-blocking therapies on the hormone-blocking therapy page. 


Trastuzumab is used for the treatment of HER2-positive breast cancer. About 15-20% of breast cancers are HER2-positive. 

HER2 is a protein found on the surface of cells, and HER2-positive breast cancers have a lot more HER2 than other breast cancers. Trastuzumab works by stopping HER2-positive cancer cells from growing and dividing. 

For people with early breast cancer that is HER2-positive, trastuzumab is most commonly given with chemotherapy, either before or after surgery. 

Side effects 

Trastuzumab can cause heart problems in some people. Before starting treatment, your doctor will check your heart function and it will be checked again at regular intervals while you are receiving treatment. This can detect any weakening of the heart before symptoms occur and treatment can be modified if necessary. Your medical oncologist will discuss any possible benefits and drawbacks of taking trastuzumab as part of your treatment. 

Other HER2 targeted therapy 

Kadcyla (trastuzumab emtansine) is a targeted therapy that may be used to treat early breast cancer. Kadcyla may be recommended to you if you have neoadjuvant anti-HER2 treatment and have cancer cells remaining in your breast and/or lymph nodes after this treatment is completed. 

New targeted therapies for early breast cancer continue to emerge with some being tested in clinical trials. 

More information 

  • To find more information on targeted therapies, visit My Journey. 
  • Join our Online Network if you think that talking to others online and sharing experiences will help.  
  • Read more about targeted therapies on the Cancer Australia website. 

BCNA’s My Journey  

My Journey is where you go to get all your breast cancer information about your diagnosis in one place. Whether you have early breast cancer, DCIS or metastatic breast cancer, My Journey provides you with the latest information tailored to suit your situation. You can access this information through My Journey via an app or web browser at