Breast cancer in women, hormone and HER2 receptors
Breast cancer cells often have receptors (proteins) that hormones or other proteins can attach to and stimulate the cancer to grow. A pathologist will do tests on the cancer cells to find out if receptors are present and what type they are.
The results of these tests will help you and your doctor to decide on the most effective treatment for you.
Breast cancers with receptors for the hormone oestrogen are called oestrogen-receptor positive or ER positive breast cancer. About 70% of breast cancers are ER positive. They respond well to treatment with hormonal therapies.
Oestrogen-receptor negative or ER negative breast cancers don’t have hormone receptors. ER is used because the American spelling of oestrogen is estrogen.
Some breast cancers have high numbers of receptors for the protein HER2 (human epidermal growth factor 2). They are called HER2 positive breast cancers. About 1 in 7 women (15%) with early breast cancer have HER2 positive cancer. A drug called trastuzumab (herceptin ®) is an effective treatment for this type of breast cancer.
If the cancer does not have receptors for either HER2 or the hormones oestrogen and progesterone, it is called triple negative breast cancer. It affects up to 1 in 5 women (15–20%) with breast cancer and is more common in younger women.