What are alternative methods to IHC testing for determining cancer biomarkers and receptor status?
If your IHC results are unclear (scored as 2+ or "equivocal"), fluorescence in situ hybridization (FISH) testing is the main alternative method used. FISH is actually more precise than IHC because it directly measures the Show Full Answer
What are alternative methods to IHC testing for determining cancer biomarkers and receptor status?
If your IHC results are unclear (scored as 2+ or "equivocal"), fluorescence in situ hybridization (FISH) testing is the main alternative method used. FISH is actually more precise than IHC because it directly measures the number of HER2 genes inside cancer cells rather than just looking at protein levels on the cell surface.
FISH uses a special dye that binds to the HER2 gene in breast cancer cells. The sample is examined under a microscope to count extra gene copies. This helps determine if your cancer is truly HER2-positive or negative when IHC results aren't definitive.
The good news is that you typically won't need another biopsy procedure - the pathologist can use cells from your original biopsy sample for FISH testing. This test takes similar timing to IHC, usually several days to a couple of weeks depending on lab availability.
Both tests together help doctors accurately determine your hormone receptor status and HER2 status, which guides treatment decisions about whether targeted therapies like Herceptin or hormonal therapies will work best for you.
November 23, 2025
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