What do the results mean?If HER2 protein levels are higher than normal or extra copies of the HER2 gene are found, it probably means you have HER2-positive cancer. If your results show normal amounts of HER2 protein or the normal number HER2 genes, you probably have HER2-negative cancer.If your results were not clearly positive or negative, you will probably get retested, either using a different tumor sample or using a different testing method. Most often, IHC (testing for the HER2 protein) is done first, followed by FISH (testing for extra copies of the gene). IHC testing is less expensive and provides faster results than FISH. But most breast specialists think FISH testing is more accurate.Treatments for HER2-positive breast cancer can substantially shrink cancerous tumors, with very few side effects. These treatments are not effective in HER2-negative cancers.If you are being treated for HER2-positive cancer, normal results may mean you are responding to treatment. Results that show higher than normal amounts may mean your treatment is not working, or that cancer has come back after treatment.Learn more about laboratory tests, reference ranges, and understanding results.
