Breast cancer may develop in one part of the body, but it’s not just one disease. In fact, oncologists think of breast cancer as at least three different types of diseases.
Triple-negative breast cancer (TNBC) describes breast cancer cells that do not have estrogen, progesterone, or HER2 receptors. It makes up approximately 15 percent of all breast cancers and is typically more aggressive than the other two types, estrogen receptor-positive breast cancer and HER2-positive breast cancer.
“It may be the smallest group, but TNBC still represents thousands of women with breast cancer, so it is a very important group for us,” says Erica Mayer, MD, MPH, a medical oncologist at Dana-Farber’s Susan F. Smith Center for Women’s Cancers.