| General Information: |
The HER2 oncogene is overexpressed in 25-30% of human breast cancer. In 90-95% of these cases, the overexpression is a direct result of gene amplification. This amplification correlates with a poor clinical prognosis, and therefore, amplification status has become increasingly important in therapeutic decisions for patients with breast cancer. Specifically, women with breast cancer are eligible for treatment with the monoclonal antibody trastuzumab (Herceptin, Genentech) which targets the HER2 gene product, p185HER-2/neu, if they show amplification and/or overexpression of HER2. Both immunohistochemistry (IHC) and FISH allow for direct detection of HER2 status in individual cells while maintaining critical architectural tissue information. Pauletti et al. (2000) have shown that FISH is actually more sensitive and specific than IHC in formalin-fixed, paraffin-embedded tissue sections, likely due to the antigenic alterations that are caused by standard fixation procedures. Press et al. (2002) further argue that FISH testing should be considered the standard of care for determining HER2 status in breast cancer. |
