FISH testing

FISH stands for fluorescence in situ hybridisation. It is a test that looks for gene changes in cells. Genes are made of ​DNA​ . They control everything the cell does, including when it grows and reproduces. FISH tests look for specific genes or parts of genes. 

Changes in genes can make the cancer cell:

• produce particular proteins

• make far more of the protein than normal

• stop making a particular protein

If a gene change occurs, the cell may produce too much of a protein or not enough. This can make the cancer cells grow and reproduce more than normal.

Cancer treatment

There are now cancer treatments that target specific proteins. It helps your doctor to know if your cancer has a particular change in its genetic make up. This can tell them whether a particular treatment is likely to work for you. 

Breast cancer

Some breast cancers produce too much of the protein ​HER2​ because of a change in a gene called HER2/neu. If doctors need to find out more about HER2 levels, they can arrange a FISH test. It can show if the breast cancer is HER2 negative, HER2 positive or HER2 low. 

Your doctor will work out the best treatment for you depending on the results of the test.