Targeted therapies for breast cancer

Targeted therapies work by blocking the growth and spread of cancer by interfering with the biology of the cancer cells.

When are targeted therapies used?

For women who have HER2-positive breast cancer. The targeted drugs block the receptors on the cells, so that HER2 proteins can’t attach to the cells and help them to grow. The drugs also help the immune system to target and kill the cancer cells.
For some types of metastatic breast cancer.

The drugs most commonly used for breast cancer are monoclonal antibodies. For example, trastuzumab and pertuzumab. These drugs are only used for HER2 positive breast cancer.

Your cancer can be tested for HER2 levels at the time of your surgery or from a biopsy.

How are targeted therapies given?

You may have targeted therapy before or after surgery, or both. Usually the drugs are given into a vein through a drip or as an injection. Other drugs may be given as a tablet.

You may have a combination of different drugs. For example, you may have a targeted therapy drug and chemotherapy.

Side-effects of targeted therapies

Side-effects depend on the drugs being used and vary from person to person. Side-effects include:

Higher risk of getting an infection
Vision changes (blurred vision, double vision, flashing lights)
Diarrhoea or constipation
Loss of appetite
Feeling sick (nausea)
Feeling very tired (fatigue)
Heart problems, for example, changes to your blood pressure or heart rhythm, or your heart muscle not working properly.

Your doctor and nurse will explain your treatment in more detail and tell you about any likely side-effects. Tell your doctor or nurse if you don’t feel well or if any symptoms are troubling you.

For more information on targeted therapies and their side-effects, call our Support Line on 1800 200 700 or visit a Daffodil Centre. Read more about coping with side-effects.