Some breast cancers respond to hormones in our body and their growth is driven by the presence of these hormones - these are known as oestrogen and progesterone receptor positive breast cancers. 

Other breast cancers respond to the presence of the HER2 protein and will grown in response to this receptor - this is known as HER2-postive breast cancer.

Triple negative breast cancer, means the growth of breast cancer cells is not driven by:

  • oestrogen
  • progesterone
  • HER2

About 10 to 20 per cent of all breast cancers are classified as triple negative. This type of breast cancer often affects younger women and those with the breast cancer gene BRAC1.  Triple negative breast cancer also tends to be more aggressive than other forms of breast cancer. 

Triple negative breast cancer is usually treated with surgery, radiation therapy and chemotherapy, but it does not respond to hormonal treatments such as aromatase inhibitors, SERMS and ERDs or medicines which impact on the HER2 protein, such as Herceptin and Tykerb.

Research is underway into new medications which may be more effective in treating triple negative breast cancer.