Trastuzumab (Herceptin)

• What is Trastuzumab (Herceptin)?
• How does Trastuzumab work?
• HER2 diagnosis

What is Trastuzumab (Herceptin)?

Trastuzumab is a common type of targeted therapy (sometimes called biological therapies) used to treat HER2+ breast cancer.

You will be told about the HER2 status of your breast cancer when pathology tests are done following cancer surgery. Trastuzumab will only be suitable if your breast cancer cells are HER2 positive, according to the Silver-in-Situ Hybridization (SISH) test (scroll down for more on the test).

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How does Trastuzumab work?

When human epidermal growth factor attaches itself to HER2 receptors on breast cancer cells, it can stimulate the cells to divide and grow.

Trastuzumab works by attaching itself to the breast cancer cell receptors to prevent cells from growing. After it binds to HER2 receptors, Trastuzumab encourages the body's immune system to help destroy cancer cells. Other targeted therapies are being tested in trials.

In deciding whether or not to have Trastuzumab:

• It is important to access quality information to make informed decisions
• It is important to be aware of possible side-effects and strategies to manage these – such as fatigue and cardio-vascular problems
• As with many breast cancer drugs, there are important things that we still do not know about Trastuzumab. Clinical trials to answer these questions are ongoing and more information will become available in the future.

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HER2 diagnosis

About one in five breast cancer patients have HER2+ breast cancer.

HER2, or Human Epidermal Growth Factor Receptor 2:

• Is a protein found on the surface of some breast cancer cells
• Is made by a specific gene called HER2/neu gene
• Acts as a receptor for a particular growth factor called epidermal growth factor which occurs naturally in the body. Breast cancer cells that have a high level of these receptors are called HER2 positive (or HER2+).

Several tests are available to measure HER2 levels. The most definitive test for HER2 status is the SISH test. Testing can be done at the same time as initial cancer surgery, or samples of cancer cells from previous biopsies or surgery can be used.

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• How is Trastuzumab treatment different from chemotherapy?
• Can I benefit from treatment with Trastuzumab alone, without chemotherapy?
• How much will Trastuzumab cost?
• When will I start Trastuzumab if I am having other treatments?
• Will I need to go to hospital to receive Trastuzumab?
• Should I do anything in particular to prepare for having treatment?
• How often will I have treatment?
• How long is treatment duration?
• Will I need any extra tests? How much will the extra tests cost?
• What are the possible side effects of Trastuzumab?
• When are side effects likely to occur?
• Who should I talk to if side effects occur?
• How can I manage side effects if they occur?
• Will the side effects stop or improve when I finish treatment?