What is a cell?
Cells are tiny spheres that make up all of the organs and tissues in your body. Cells also make up cancerous tumors. Cells are too small to see with your eyes.

What is HER-2/neu?
HER-2/neu (also known as HER-2) is a protein that is found on the surface of breast cells. It sends messages to the cell from "growth factors" outside the cell. Growth factors tell cells to grow and divide.

What does it mean to be HER-2/ neu positive?
Everyone has the HER-2/neu protein. But in some breast cancers, the cells produce many more HER-2/neu proteins than normal. These breast cancers are called "HER-2/neu positive cancers." Breast cancers that have very few HER-2/neu proteins or none at all, are called "HER-2/neu negative cancers." It is sometimes unclear whether women with low levels of HER-2/neu are actually HER-2/neu positive or negative. HER-2/neu positive breast cancers grow faster than HER-2/neu negative breast cancers.

What treatments are available for women with HER-2/neu positive breast cancer?
Herceptin is a drug that can block HER-2/neu and prevent HER-2/neu positive cancers from growing. It is an effective treatment in many women with metastatic, HER-2/neu positive breast cancer. But the drug has little effect on women with HER-2/neu negative breast cancer. Clinical trials are being done right now in order to see whether or not Herceptin can help women with early breast cancer. ?