What does FISH test mean on a biomarker or pathology report?
FISH is a lab test that counts copies of a gene, such as HER2, inside the cells. It is often used to confirm a borderline result from another test. Results are reported as amplified (extra copies) or not.
Also written as
- FISH
- fluorescence in situ hybridization
- ISH
- in situ hybridization
Please read: This page explains general report language and cannot interpret your personal report, diagnose a condition, judge how serious a result is, or recommend treatment. Only your care team can do that.
How to read receptors & markers results
Receptor and biomarker results describe features of the cancer itself — proteins, hormone receptors, or gene changes that can point toward treatments more likely to help. A result is usually reported as positive or negative, a percentage, or a score, and the cut-off that counts as 'positive' can differ by cancer type and by lab. These tests are powerful for matching treatment, but one marker is only part of the plan, and borderline results are sometimes repeated or confirmed with a second method. Your oncologist reads each marker alongside the rest of your testing.
Questions to ask your care team
- Which markers were positive or negative, and how do they affect my treatment choices?
- Do any of my results open up targeted or hormone therapies?
- Should any borderline result be repeated or confirmed another way?
- Is more molecular or genomic testing worth doing in my case?
Related receptors & markers terms
- Estrogen receptor (ER)The estrogen receptor (ER) test shows whether breast cancer cells have receptors for the hormone estrogen.
- Progesterone receptor (PR)The progesterone receptor (PR) test shows whether breast cancer cells respond to the hormone progesterone.
- HER2 statusHER2 is a protein that can make some cancers grow faster.
- Triple negativeTriple negative breast cancer tests negative for ER, PR, and HER2.
- Hormone receptor statusHormone receptor status combines the ER and PR results.
- Oncotype DXOncotype DX is a gene test done on some breast cancers that gives a 'recurrence score.' The score helps estimate the chance the cancer could come back and whether chemotherapy is likely to help.
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