Main MBC subtypes

• HR+/HER2-

• HR-/HER2- (mTNBC)

• HR+/HER2+ (Triple Positive)

• HR-/HER2+

HR stands for hormone receptor. HR+ means that tumor cells have receptors for the hormones estrogen or progesterone, which can promote the growth of HR+ tumors. HER2 stands for human epidermal growth factor receptor 2. HER2+ means that tumor cells make high levels of a protein called HER2/neu, which has been shown to be associated with certain aggressive types of breast cancer.

HER2-low describes a breast cancer subtype "in between" HER2-positive and HER2-negative. The cancer cells have some HER2 protein on their surfaces but not enough to be considered HER2-positive.

Oligometastatic cancer describes an intermediate stage of cancer between localized and widely spread disease. We classify oligometastatic as a subclass of stage IV cancer. If you have oligometastatic cancer, that means cancer has spread to fewer than five sites in your body