Approximately 20% of breast cancers are known as HER2 positive. This means that a gene mutation has caused the cells to have an over expression of HER2 receptors and this protein signals the cancer cells to grow and divide.
The HER2 receptor can be tested for by:
- Immunohistochemistry (IHC)- which shows how much of the protein is on the cell surface
- In-situ hybridisation (ISH)- which tests the number of copies of the gene inside the cell..
HER2 positive breast cancers tend to be more aggressive than HER2 negative cancers.
Trastuzamab (Herceptin) is a biological therapy that has been designed to specifically target the HER2 receptor in HER@ positive breast cancer. It reduces the risk of recurrence and death in women with HER2 positive breast cancer and prolongs survival in women with HER2 positive metastatic breast cancer.
Lapatinib (Tykerb) is another “HER receptor blocker” that is sometimes used in combination with Herceptin
Although Herceptin has been shown to have greatest benefit when used in combination with chemotherapy, it is not in itself a chemotherapy treatment. Chemotherapy treatments affect all rapidly dividing cells whether they are cancer cells or healthy cells.
Herceptin, however, targets only those abnormal cells with increased display of the HER2 receptor and it spares the healthy cells.
For this reason the side effect profile is substantially less.
Its main possible side effect is on the heart and the use of Herceptin in some patients may require baseline and periodic cardiac function tests. This side effect is usually reversible. In some cases hypersensitivity or allergic reactions can occur and for this reason it should be given in an appropriately equipped facility by staff who are trained to manage a possible reaction. Other less common and mild side effects may include fever, throat irritation and runny nose.
It is an intravenous therapy administered via a peripheral drip into a vein ideally every 3 weeks for one year.
However, it is unfortunately extremely expensive, not yet available in State hospitals and not covered by many Medical Aid schemes.
For those who can afford it, or those whose medical aids will cover it, Herceptin has significantly improved the prognosis and survival of patients with HER2 positive breast cancers to the extent that the outcomes are even better than some patients with HER2 negative breast cancers!
This blog was kindly supplied by Ronelle de Villiers at http://www.capebreastcare.org