When found, breast cancer is tested for three primary cell surface receptors to identify treatment options. Those are the estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER-2). Triple-negative breast cancer (TNBC) tests negative for all three (or limited for HER-2 receptors).

TNBC cells can break away from the original tumor in the breast and travel to other parts of the body, most often the bones, lungs, brain or liver. When this happens, it’s known as metastatic TNBC. Once the cancer has spread through the body, complete removal is unlikely. However, while this means the cancer may not go away completely, treatment can help.