Why is it clinically important to determine HER2 status?
• A: HER2 is both a prognostic and predictive marker. HER2 is overexpressed in approximately 25% of all primary breast cancers and is associated with aggressive tumors and poor outcome. Knowing the HER status of the tumor can help predict what types of therapies will be most beneficial. Because of this, the NCCN recommends HER2 status determination on all newly diagnosed invasive breast cancers (NCCN, v2.2008). Detection of HER2 protein expression, either directly through IHC or indirectly through gene amplification, is necessary for selection of patients appropriate for Herceptin therapy. • NCCN Guidelines: Patients with tumors that are HER2-positive may derive benefit from treatment with Herceptin as a single agent or in combination with selected chemotherapeutic agents. NCCN recommends selecting patients for Herceptin therapy who have tumors that are either positive for HER2 by FISH or 3+ by IHC. Patients whose tumors are IHC 0 or 1 + or FISH negative have very low rates of Hercepti
