Triple-negative breast cancer is a less common type of breast cancer. Triple-negative means that the breast cancer cells don’t have three things—estrogen receptors, progesterone receptors, or large amounts of HER-2 protein.

This type of breast cancer tends to spread more quickly than other types. Treatments such as hormone therapy and some medicines that target HER-2 don’t work well on this type of cancer. But chemotherapy can be effective.