Should one be assessing HER-2 at the DNA level or the gene product (protein) level?
Extra copies of the HER-2 gene drive excess protein on the surface of the cell. HER-2 assessment at a direct molecular level by FISH has been shown to be more accurate than IHC antibody-based tests.1 Responses in IHC 2+ and 3+ MBC patients treated with single-agent Herceptin were seen exclusively in FISH positive patients2.
