Trastuzumab is a monoclonal antibody which targets breast cancer cells that over-express the HER2 protein. Approximately 20%3 of newly diagnosed breast cancers have HER2 gene amplification, leading to over-expression of the HER2 protein. HER2 over-expression is associated with adverse prognostic factors including large nuclear size, high nuclear grade, and decreased expression of oestrogen and progesterone hormone receptors, together with reduced disease-free and overall survival for patients with node-positive or node-negative breast cancer. By binding to HER2 protein receptors, trastuzumab interrupts the growth signal, thereby slowing the growth and spread of breast cancer cells. For information on HER2 testing see: Assessment of HER2 Status.
Recommendations for use of Trastuzumab (Herceptin®)