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Biological therapy treatment

Find out about having biological therapy for breast cancer, including how you have it and the possible side effects.

Biological therapies are drugs that change the way cells work and help the body control the growth of cancer.

Some seek out and destroy cancer cells. Others help the body attack the cancer.

Our immune system works to protect us against diseases, including cancer. It normally picks up faulty cells and destroys them. Sometimes the immune system misses these and cancer develops. Scientists are working on ways to trigger the immune system so it can target cancer cells.

Trastuzumab (Herceptin)

Trastuzumab has the brand name Herceptin. It's a monoclonal antibody. Monoclonal antibodies attach to proteins on or in cancer cells.

Diagram showing a monoclonal antibody attached to a cancer cell

Before you start

Between 20 and 25 out of every 100 people with early breast cancer (20 to 25%) have HER2 positive breast cancer. A sample of your tumour (biopsy) will show if it's HER2 positive. 

You'll have blood tests and a heart scan before you start.

When you have it

You usually have trastuzumab after surgery and chemotherapy (and radiotherapy if you need it). You can have trastuzumab every 3 weeks for a year.

Doctors also give biological therapies, including trastuzumab, for breast cancer that has spread to another part of the body (advanced breast cancer).

How you have it

You normally have trastuzumab into your bloodstream through a drip in your arm. Or by an injection under your skin.


Researchers are looking into new types of biological therapies for breast cancer. Some research is looking into using biological therapies alongside chemotherapy to see how they work together.

You may have biological therapies other than trastuzumab as part of a clinical trial.

Side effects

The side effects of biological therapies are different depending on the drug you're having. Not everyone gets all side effects. Side effects include:

  • allergic reaction
  • diarrhoea
  • tiredness
  • flu-like symptoms including fever, muscle aches and sickness
  • low blood counts

Trastuzumab can cause some damage to the heart. You'll have regular checks to see how well your heart is working.

When you go home

Treatment with biological therapies can be difficult to cope with. Your nurse will give you numbers to call if you have any problems at home.

Tell your doctor or nurse about any problems or side effects you have.

Information and help

Dangoor sponsorship

About Cancer generously supported by Dangoor Education since 2010.