ZocdocAnswersWhat is a FISH test?

Question

What is a FISH test?

I'm a young woman and I just found a lump in my breast that I am getting biopsied to determine whether it is cancerous. The doctor talked about using a FISH test to make this decision, but I don't know what that means. Do I have to do anything else for the FISH test? What do we learn from it?

Answer

This is an example of how we as physicians need to do a better job explaining our terminology to our patients. In this case FISH is a new type of genetic test that may help aide in determining a cancer cell's likelihood of metastasizing. Let me explain. FISH stands for florescence in situ hybridization. It is designed to detect structural abnormalities in the DNA of your cells. Through recent research, specific DNA abnormalities have been identified as markers for a cell's risk of becoming metastatic. FISH is currently one of the techniques available to look for these changes in the DNA. This helps us determine what additional tests, therapies, or procedures need done to minimize your risk of developing metastatic breast cancer. The test does not tell us if you have breast cancer metastases, and thus it cannot be the only test used. I suggest that you schedule another appointment with the physician who ordered the biopsy. By now, the results are likely back. Have him or her explain the FISH test in detail and explain the result if they are back. Likely the results will be able to help in determining what is you next step in treatment. Good luck.

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