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Two Oncologists, two Labs, different pcr results...perplexing

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#1 critchhwc


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Posted 14 June 2014 - 02:41 PM

In January, when I learned I was no longer in MMR (.083 to .537) I decided to see a second oncologist (the one who originally diagnosed my CML..  His PCR came back 0.220.  Though the two were quite a bit different they indicated I was no longer in MMR.  I increased my Geevec to 600 mg daily.  This week I received my most recent PCR results from both Oncologists.  One showed that I had once again achieved MMR with 0.040, but the other lab reported that I had gotten worse (0.220 to 0.390).  We are all scratching our chins over this.  Both labs are showing all my other values (cbc and white differential) to be normal.  We have decided to run pcr's again in 2 months, as long as the other values remain normal.  I will continue on Gleevec 600 mg.

Thoughts Please.

#2 Trey


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Posted 14 June 2014 - 10:43 PM

This points out once again that PCR tests are not nearly as accurate as the multiple decimal points might imply.  They are only accurate to 1/2 log, which is not very impressive.  This inaccuracy is because a PCR is not an actual percentage of leukemic cells in the sample, but rather an estimate regarding the ratio of leukemic genes (BCR-ABL)  to another normal gene in the body (usually ABL1), but only after a series of heating cycles.  It is like estimating the annual rainfall from many years ago by cutting a tree and looking at the tree rings. 

#3 Melanie


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Posted 16 June 2014 - 04:00 PM

Due to a clinical trial I'm in, I have had PCR's done at two different labs for quite a while. Since I have an out of state oncologist for the trial and a local oncologist, they will only track the trend from the lab they use, due to the variances that labs have, even with the IS.  Of course I compare the two all the time and they are usually about 1/2 to a full log different. But when I just track the trend of each individual lab, it's a much better look. It's those full log or more differences that make you crazy!  Like Trey says, they are estimates and if each lab can be off by a 1/2 log, they may actually be closer than they look.  

Hope both labs show MMR for you in two months!

Dx - 05/2011; PCR: 15.04; Fish: 87% Slow responder due to pancytopenia. Current - Bosulif - Nov: 2012, Mar 2016 lowered to 300 mg. 07/16 back to 400 mg. Clinical trial drug, Promacta, Feb 2013, for low Platelets.
CyCR - Aug 2014, Positive for 1 chromosome Sep 2015. PCR: 12.77 in Oct, 2012 to 0.04 (MDA) in Mar, 2016. 4/2016 - 0.126 (Local lab (IS); 05/2016 - 0.195 (local); 6/2016 - 0.07 (MDA); 7/2016 - 0.03 (local) 9/13/2016 - 0.16 (MDA); 9/26/2016 - 0.31 (MDA); 11/2016 - 0.012 (local); 01/2017 - 0.24 (MDA); 04/2017 - 0.09 (MDA); Cytogenetics show der(1:7)(q10;p10)7 chromosome mutation. Repeat of Sep 2015. PCR - 6/2017- 0.035 (local); 10/2017- 0.02 (MDA)

#4 HowYouDoing


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Posted 02 July 2014 - 09:44 AM

Is one of the labs NeoGenomics out of Florida? I had some unexpected results come back from that lab - the number was higher than what we expected to see.  My Onc said he has been seeing a lot of unexpectedly higher numbers come back for most of his patients over the last few months. 

Heather - CMLer since 3/2010 - Gleevec 400 til 11/2013 now Sprycel 100.  :)  

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