What is triple-negative breast cancer?
About 10 to 20 percent of breast cancers are triple-negative.
Knowing breast cancer basics can help you understand how triple-negative breast cancer is different from other types of breast cancer. Doctors search for the presence or absence of three receptors, proteins that live inside or on the surface of a cell and bind to something in the body to cause the cell to react. You may have heard of the oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2).
In oestrogen receptor-positive breast cancer, progesterone receptor-positive breast cancer and HER2 positive breast cancer, treatments prevent, slow or stop cancer growth with medicines that target those receptors. But triple-negative breast cancers need different types of treatments because they are oestrogen receptor negative, progesterone receptor negative and HER2 negative. Medicines like tamoxifen, which targets the oestrogen receptor, and trastuzumab (Herceptin), which targets HER2, are not helpful in treating triple-negative breast cancer. Instead, chemotherapy has been shown to be the most effective treatment for triple-negative breast cancer.
Researchers are working to improve their understanding of the biology of triple-negative breast cancers, how these types of cancers behave and what puts people at risk for them. Their goals are to find out the best ways to use treatments that already exist and to develop new ones.
Understanding the ‘Basal-like’ Subtype
Most triple-negative breast cancers have a basal-like cell pattern. This term means the cells look like the basal cells that line the breast ducts, the tubes in the breast where milk travels.
Basal-like breast cancers tend to over express, or make too much of, certain genes that encourage cancer growth. Not all triple-negative breast cancers are basal-like, and not all basal-like breast cancers are triple-negative. About 70 to 90 percent of triple-negative breast cancers are basal-like.
Doctors choose treatments because the cancer is triple-negative, not because it is basal-like. The basal status of the cancer does not factor into treatment decisions