Her2 Page

HER2-positive breast cancer is a particularly aggressive type of the disease

Approximately one in five women diagnosed with breast cancer will have HER2-positive disease. This is a particularly aggressive form of breast cancer which, if left untreated, is associated with faster disease progression and poorer chances of survival than HER2-negative disease. Globally, approximately 334,000 women are diagnosed with this type of breast cancer every year.1

 While a normal cell has approximately 20,000 HER2 proteins on its cell surface, a HER2-positive cancer cell has an estimated two million HER2 proteins per cell.3,4

HER2-positive breast cancer is characterised by the presence of a specific protein (receptor) called the Human Epidermal Growth Factor Receptor 2 (HER2).2 The HER2 protein is present on the surface of healthy cells and plays an important role in their natural life cycle. Its job is to signal or ‘tell’ them to grow and divide. However, excessive amounts of HER2, due to a gene mutation, can lead to uncontrolled cell growth and the development of cancer. A HER2-positive cancer cell has approximately two million HER2 proteins on its surface – around 100 times more than a normal cell.3,4

The HER2 protein has also been found to pair with other members of the HER family which are present on the surface of a cell – HER1, HER2, HER3 and HER4. This act of pairing can send additional signals to the cell, further encouraging cancer growth and survival.4

There are four proteins in the HER family and HER2 has been found to pair with other HER family members, potentially driving cancer growth.4

Treatment developments in the last 15 years have changed the natural course of HER2-positive disease5

Significant progress has been made in the treatment of HER2-positive breast cancer. Today, several treatments are available which specifically target HER2, blocking the signals that cause cancer cells to grow and multiply. These targeted treatments have improved the survival outlook for patients with HER2-positive breast cancer, to the extent that patients treated with these medicines now typically experience better outcomes than people with less aggressive HER2-negative disease.5 However, despite the huge progress that has been made, up to one in three patients with HER2-positive breast cancer, who are diagnosed before their cancer has spread, known as early breast cancer (eBC), will see their disease progress to an advanced stage, where it is no longer curable. Furthermore, some patients with this aggressive disease are at an even higher risk of relapse.6

Due to the aggressive nature of HER2-positive breast cancer, it is important that patients are diagnosed and treated early

For those people who are diagnosed before their cancer has spread, known as early or locally advanced breast cancer, early treatment provides the best chance of cure.7 However, many women are still being diagnosed at the stage when their cancer has spread to other parts of the body, such as the brain or liver, meaning cure is no longer a possibility. In these cases catching the disease early allows for early discussion and planning of a tailored treatment plan, which may ultimately improve patient outcomes.

References

1. Ferlay J, et al. [Online]. Available from: http://globocan.iarc.fr [Accessed 6 September 2016].

2. WebMD, Types of Breast Cancer: ER Positive, HER2 Positive, and Triple Negative. [Online]. Available from: http://www.webmd.com/breast-cancer/breast-cancer-types-er-positive-her2-positive [Accessed 2 September 2016].

3. Lewis Phillips G, et al. Cancer Research 2008;68:9280-9290.

4. Iqbal N and Iqbal N. Molecular Biology International 2014;doi:10.1155/2014/852748.

5. Dawood S, et al. Journal of Clinical Oncology 2010;28(1):92-8.

6. Jackisch C, et al. San Antonio Breast Cancer Symposium 2015;Abstract PD5-01.

7. Cancer Research UK [Online]. Why is early diagnosis important? Available from: http://www.cancerresearchuk.org/about-cancer/cancer-symptoms/why-is-early-diagnosis-important [Accessed 12 September 2016]