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.
FISH Higher than Pcr?
Posted 01 December 2017 - 04:23 PM
Posted 01 December 2017 - 04:59 PM
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.
Diagnosed 11 May 2011 (100% FiSH, 155% PCR)
with b2a2 BCR-ABL fusion transcript coding for the 210kDa BCR-ABL protein
Sprycel: 20 mg per day - taken at lights out with Quercetin and/or Magnesium Taurate
6-8 grams Curcumin C3 complex.
2015 PCR: < 0.01% (M.D. Anderson scale)
2016 PCR: < 0.01% (M.D. Anderson scale)
March 2017 PCR: 0.01% (M.D. Anderson scale)
June 2017 PCR: "undetected"
September 2017 PCR: "undetected"
Posted 01 December 2017 - 09:10 PM
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.
Posted 02 December 2017 - 11:53 AM
Bravo - wisdom that fits on an index card . . .
Dx July 2009 on routine physical. WBC 94. Started Gleevec 400 mg Sept 2009. MMR at 2yrs. Side effects (malaise, depression/anxiety, fatigue, nausea, periorbital edema) never improved. Kidney issues developed because of Gleevec. Switched to Sprycel 70 mg in Aug 2011. Above side effects disappeared or improved. Have been MR3.5 - 4.5 ever since. Two untreated pleural effusions followed by one treated by stopping Sprycel Jan 2017. After 9 weeks, PCR showed loss of MMR; re-started Sprycel at 50 mg and in 3 months was back to <0.01% IS. Pleural effusion returned within a couple of months, same as before (moderate, left side only). Stopped Sprycel 50 mg for 12 weeks; pleural effusion resolved. At about a monthoff the drug, PCR was 0.03; at 11 weeks it was 2.06 - lost CCyR? Have returned to 50 mg Sprycel for 3 weeks, intending to reduce to 20 mg going forward.
Posted 02 December 2017 - 07:15 PM
Posted 02 December 2017 - 07:41 PM
Posted 12 December 2017 - 04:13 PM
Posted 13 December 2017 - 07:20 PM
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.
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