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how common are transient pcr increases?

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#1 daniel1403989267


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Posted 06 December 2011 - 06:21 PM

Hi all,

I am a 4+ yr CML patient, posting here for the first time. I transferred from gleevec to tasigna about 2 years ago due to moderate side effects on gleevec and lack of complete efficacy (I did not attain MMR). My PCR value has remained lowish (2.5-3 log reduction) since about 18 months into treatment, but has never been undetectable. I had a transient PCR increase in a single assessment about a year ago. I just had another increase (from ~3 log to ~2.7 log reduction) at my last test. All recent tests were performed on the same instrument and quantified in the same fashion, as far as I can tell.

My onc wants to retest in 6 weeks. I wonder how concerned I should be? Should I get mutation testing? Agitate for a switch to Sprycel? Has anyone else experienced transient PCR fluctuations in patients after years of therapy, or is this general indicative of resistance? I have heard anecdotes of PCRs wavering around PCRU, but in my case the level is somewhat higher.


#2 Trey


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Posted 06 December 2011 - 06:32 PM

Quite common.  The companies that make the PCR equipment and reagents advertise that the PCR results can vary by as much as 1/2 log, even on the same sample.  The variation is usually not that bad, but that gives you some idea that these tests are not as accurate as we would like them to be.  And these companies also say that their PCR equipment is for research only, not for medical diagnostics.  Lawyers.....but again, we put far too much credence in the individual PCR results.  Trend lines are far more useful.

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