“Triple negative” is the term used to describe tumors that are ER-negative, PR-negative, and HER2-negative. It’s estimated that about 20% of breast tumors are triple negative. These tumors do not respond to hormone therapy or HER2-targeted therapies. They do, however, respond well to chemotherapy. Also, many clinical trials are now underway looking at new treatments for triple negative tumors. For additional information about triple negative breast cancer, please visit: Triple Negative