Yesterday, I posted about a diagnostic test used for CLL called flow cytometry. Another modern test that is also used extensively is known as FISH (Fluorescence In Situ Hybridization). Like flow cytometry, it is also a fairly expensive test to have run. According to WebMD:
How FISH Works
During a FISH test using a sample of the patient’s tissue, special colored dyes are attached to specific parts of certain chromosomes in order to visualize and count them under a fluorescent microscope and to detect cancer-promoting abnormalities.
Abnormalities found in cancer cells include:
- Translocation. Part of one chromosome has broken off and relocated itself onto another chromosome.
- Inversion. Part of a chromosome is in reverse order although it is still attached to the correct chromosome.
- Deletion. Part of a chromosome is missing.
- Duplication. Part of a chromosome has been copied and the cell contains too many copies.
Translocations can help doctors identify some types of leukemia, lymphomas, and sarcoma. Duplications in breast cancer cells can help doctors choose optimal treatments.
Compared to standard cytogenetic (cell gene) tests, one advantage of FISH is that it can identify genetic changes that are too small to be seen under a microscope. Another advantage is that FISH doesn’t have to be performed on cells that are actively dividing. Because other tests cannot be performed until cancer cells have been growing in lab dishes for about two weeks, the process usually takes about three weeks. FISH results are usually available within a few days.
Wikipedia has a good article on Fluorescence In Situ Hybridization if you’re interested (or having trouble sleeping).