Illustration of triple negative breast cancer cells. Triple negative breast cancer cells don't have receptors for the hormones oestrogen and progesterone or the human epidermal growth factor receptor 2 (HER2) protein. Around 15 per cent of breast cancers are triple negative. It is a fast-growing cancer that is more likely to spread than other types of breast cancer. Treatment is with surgery, radiotherapy or chemotherapy, often in combination. There are fewer treatment options for triple negative breast cancer, as hormone therapies and drugs used to treat other breast cancers target the missing receptors.