triple negative

Definition of triple-negative breast cancer
National Cancer Institute

triple-negative breast cancer

(TRIH-pul-NEH-guh-tiv brest KAN-ser)
A type of breast cancer in which the tumor cells do not have estrogen receptors, progesterone receptors, or large amounts of HER2/neu protein on their surface. Knowing whether breast cancer is triple negative is important in planning treatment. Also called ER-negative PR-negative HER2/neu-negative breast cancer and TNBC.

Source: NCI Dictionary of Cancer Terms