7 replies to this topic

[jlegakis]

I was wondering IF a FISH result could ever be HIGHER than PCR? I have been on 800 mg. Tasigna for 15 mos. and my FISH was neg. after 3 mos. and has stayed neg. as my PCR dropped to 4.02%  over that time, BUT my FISH came in at 16%  !!! Luckily my onc called me the next day and told me it was a LAB ERROR! However, can the FISH result ever be higher than the PCR? Also, since I have been NEGATIVE FISH for over a year is it STILL necessary to have it done? I am a turtle in the CML family and my recent PCR at 4.02% is my lowest as I just dropped from 13% 3 mos. ago.

[scuba]

You are not a turtle. FISH going negative in 3 months is fast. And as your Oncologist mentioned to you, your 'sudden' FISH of 16% is an error - so ignore it. It never happened. You are still FISH negative.

 

As far as your original question. Not likely. FISH drops pretty quickly with PCR lagging. They are measuring two very different things. FISH looks at cells under the microscope. Zero to 100% is the range. PCR is a molecular measure as percent against a standard. It can be greater than 100%. A PCR of around 1% corresponds to a FISH level of zero, but only in an empirical sense. 

 

You no longer need FISH testing. PCR from here on forward is all you need - as long as PCR continues to drop and falls below 0.1% (MMR). You are heading in the right direction.

[Trey]

Thank you for your interest in theoretical statistics.  Because zero FISH is roughly equivalent to a 1% PCR (2 log reduction by IS) it is theoretically possible that for tests done during the same time frame a FISH could be about 3% when a PCR is 2%, or numbers such as these hovering just above 1.  This low number FISH/PCR dance is only possible when both are somewhere around 1 - 5%.  So a 16% FISH and a 4% PCR are inconsistent with reality.

 

For those still reading, you have no life at all.  But as entertainment and a salute to your perseverance in the face of absurdity, FISH is never expressed in less than whole numbers.  Most PCR numbers for those doing well on TKI drugs are below 1, meaning fractions.  Once a PCR becomes a fraction, it is no longer possible for the FISH to be higher than the PCR without a mistake having been made. 

Edited by Trey, 13 December 2017 - 07:16 PM.

[kat73]

Bravo - wisdom that fits on an index card . . .

[ROMO]

The bouncing ball.

 

It might be good luck or bad luck.

Let's say you don't got the CML.

Good Luck.

Let's say you got CML.

Bad luck.

 

All the other stuff is a bouncing ball.

 

You guys are my friends.

 

Romo

[ROMO]

Sorry,

 

I got poetically carried away with myself.

I will try not to let that happen again.

 

Romo

[jlegakis]

I appreciate everyone`s advice on my FISH `lab error' at 16 % with a Pcr at 4.05%.However, when I saw my ONC this morning he did NOT explicitly state ( with certainty)that it was, in fact a lab error.Rather, he just looked at the result as "Odd" and left it at that! He did say that he would be giving me a Pcr and another FISH in 3 mos.So, I felt like I was in suspended animation !?Anyway, he did say he was pleased with my Pcr dropping from 16% to 4.05% in the last 3 mos. What do you think? Should I just stick with the Pcr results? This is nerve wracking !

[Trey]

Now that you have that FISH number it would be reasonable to disprove it with another one.  But once the FISH turns negative they are usually stopped unless there is a good reason.  PCRs are used after CCyR to monitor minimum residual disease (MRD) levels.