What does it mean when the breast cancer is HER2-positive?
• A: HER2 stands for Human Epidermal growth factor Receptor 2. Each normal breast cell contains copies of the HER2 gene, which helps normal cells grow. The HER2 gene is found in the DNA of a cell, and this gene contains the information for making the HER2 protein. The HER2 protein, also called the HER2 receptor, is found on the surface of some normal cells in the body. In normal cells, HER2 proteins help send growth signals from outside the cell to the inside of the cell. These signals tell the cell to grow and divide. In HER2+ breast cancer, the cancer cells have an abnormally high number of HER2 genes per cell. When this happens, too much HER2 protein appears on the surface of these cancer cells. This is called HER2 protein overexpression. Too much HER2 protein is thought to cause cancer cells to grow and divide more quickly. This is why HER2+breast cancer is considered aggressive.
