2 replies to this topic

[jlegakis]

How does a 0% FISH correlate to a PCR value on the IS? I have been on 800 mg Tasigna for 6 mos. and my FISH was Negative after just 3 mos, BUT my PCR was 28%!! Now my latest FISH is still at 0%, BUT my PCR dropped to only 11%. Is there something amiss? I looked at the CML Guidelines/Chart and a 0% Fish translates to about 1% PCR, but my onc is NOT concerned. What do you think? Lab error?

[scuba]

Your Onc. is correct. Don't be concerned. Zero percent FISH is the gold standard, achieving that milestone at 3 months is excellent.

Once you achieve zero percent FISH - chances of your CML progressing is near zero.

 

To continue to monitor your CML status - PCR takes over where FISH leaves off. Although FISH is zero, you still have CML and likely will continue for a very long time - to live with the disease. It's just at a low state.

 

You are trending downward in PCR. In the future only PCR is what is necessary for you to track your progress. Next test should show PCR lower than it is now perhaps as low or lower than 1%, but near certainty that it will be lower than 11%.

 

FISH measures actual cells. Under the microscope no CML cells are visible. That is wonderful for you.

 

PCR measures the protein activity of the CML gene. A positive PCR informs you have CML cells active, but not enough to produce disease. PCR is like a canary in the mineshaft. It is a warning if it starts to rise. As long as it is going down and stays below 0.1% you are in a good place. Many patients do well even at higher levels of PCR, but continue with zero FISH. Also, once PCR falls below 0.1%, the amount of disease left is very very very small. It is a measure at the molecular level. The PCR number at this level can vary up or down a log in scale and still be very low level.

 

Right now, after six months, you are heading in the right direction quickly. You are doing very well.

 

Congratulations.

[Trey]

FISH is far more accurate early on than PCR.  PCR is not accurate until it gets below about 1%.  Oddly, the PCR can be off wildly at higher levels of leukemia, and becomes more accurate at lower levels of leukemic burden.  So early on trust FISH more than PCR.  After CCyR (zero FISH) all you have is PCR, so use that from now on and mainly use the trends, not specific numbers.