Breast cancer

HER2 receptor status

All breast cancers are tested for oestrogen, progesterone and HER2 receptors.

The results of these tests will indicate whether certain treatments, particularly hormone therapy and targeted treatments, might be appropriate for you based on your receptor status. You will receive your receptor status information in your pathology report.

Hormone receptor positive breast cancer

Oestrogen and progesterone receptors are proteins found on the surface of breast cells. These receptors are present in healthy breast cells, but in 70% of breast cancers, these receptors are over-expressed. These cancers are deemed hormone-sensitive, because oestrogen and progesterone can attach to the receptors and stimulate cell growth. Hormone sensitive breast cancers may be both oestrogen receptor positive (ER+) and progesterone receptor positive (PR+), or ER+ only or PR+ only. Even if the cancer cells show just a low level of hormone-sensitivity, hormone therapy can help reduce the risk of the cancer recurring.

Read more about hormone therapy

HER2 positive breast cancer

HER2 positive breast cancer is any type of breast cancer which over-expresses a protein called human epidermal growth factor receptor 2 (HER2). It may also be called HER2/neu or ERBB2. These proteins are found in normal breast cells, but are over-expressed in 15-20% of breast cancers, where they act as receptors, receiving signals which stimulate the cancer cells to divide, grow and spread at a much faster rate.

HER2 positive breast cancers tend to be more aggressive than HER2 negative cancers and are often less sensitive to hormone therapy. HER2 positive disease previously carried a bleak prognosis, but the development of targeted treatments has improved outcomes significantly. For example, chemotherapy and Herceptin (a treatment which specifically targets the HER2 receptor) administered together has been shown to reduce the risk of recurrence by up to half compared to treatment with chemotherapy alone.

Treatment for early HER2 positive breast cancer generally involves surgery, chemotherapy and Herceptin, and may include radiation therapy and hormonal therapy.

Read more about Herceptin and other targeted treatments

Triple negative breast cancer

Triple negative breast cancer (TNBC) is breast cancer that tests negative for all three receptors (oestrogen, progesterone and HER2). About 15% of breast cancers are triple negative. This type tends to occur more commonly in pre-menopausal women and people with a faulty BRCA1 gene. New Zealand statistics show that Pacific, Maori and Asian women have a higher incidence of triple negative breast cancer than Caucasian women .

People with TNBC don't benefit from treatment with tamoxifen, aromatase inhibitors or Herceptin as the cancers lack the receptors which these treatments target. There are currently no specifically targeted treatments for this form of breast cancer although many new drugs are being investigated in clinical trials.Treatment consists of surgery, chemotherapy and often radiation therapy.

In most cases, TNBC is very responsive to chemotherapy, which can be given either before or after surgery. Triple negative disease has a higher risk of recurring outside the breast in the first two to five years but a lesser risk after 5-8 years compared to other forms of breast cancer.

Download The Triple Negative Foundation’s PDF:

Guide to Understanding Triple Negative Breast Cancer.