Luminal B breast cancer

Researchers have identified four main molecular subtypes of breast cancer (also known as the intrinsic subtypes). The luminal B molecular subtype describes tumors that are estrogen receptor–positive but are more likely to have low or no progesterone receptors. They can be either HER2-negative or HER2-positive, but are more likely to be HER2-negative, and they have higher levels of the Ki-67 protein that affects cell proliferation than luminal A tumors. Some triple-positive breast cancers are luminal B. Luminal B breast cancer may not respond as well to hormone therapy as luminal A breast cancer but is more likely respond to chemotherapy. About 15 to 20 percent of breast tumors are luminal B. These cancers tend to have a poorer prognosis than luminal A breast cancers.