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Understanding PCR for 3 month checkup

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#1 Mayra



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Posted 08 February 2013 - 09:46 PM

First, I'd like to say thank you for all of the support since my diagnosis in December.  I want to understand the BCR/ABL1 test a little more before my big test on the 18th.  My original test indicates that it was 3.09% I believe it was US scale.  My doc has indicated that the lab in Texas has since changed to international.  If I'm understanding correctly based on the US scale a 1 log reduction would be .3, and a 2 log reduction would be .03.  Did I get that right? If they are switching to international scale then my score may be a little higher than the original number?  Thanks for your help with this.  Overall Sprycel is working great except for some minor  side effects like hoarse voice.  I also have a funny feeling in my throat most of the time.

#2 scuba


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Posted 09 February 2013 - 06:20 AM

Your understanding about log reduction is correct. The key is that whatever number you started at begins to drop the next time you are tested. Changing Labs or a Lab changing measurement methods (different scales) can lead to confusing results the next time. PCR can have an error range +/- one log. There is a good chance, however, that your numbers will continue to drop and that it won't be higher than it is now. You could also have a big drop and that would be excellent. Your starting level is already pretty low. My level at diagnosis was 155% bcr/abl1. So a 3 log reduction for a major molecular remission may not mean much for you as it did for me. You could have a two log reduction and be in an MMR state. You could also skip right past that and become PCRU (undetectable). Let us know your results when you get them!

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"

#3 Trey


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Posted 09 February 2013 - 11:00 AM

The log reduction issue has several variables, not just one.  Your first PCR which you referred to as "US scale" (really there is no standardized US scale, so each lab is its own individual scale) can only be compared apples to apples with other PCR results from the same lab if they did not change their testing equipment and reagents.  So assuming the lab only changed the reporting scale to International Scale (IS), you can still compare your 3.09% PCR number (your diagnosis baseline number) to subsequent percentage numbers to calculate your individual log reduction.  But the IS log reduction is based on average results for that lab using results from many CML patients.  So your individual log reduction will probably not match the IS log reduction (IS log reduction may be larger in your case).  This is especially true since your individual PCR result at diagnosis was rather low compared to most others, so you may find that your personal log reduction is disappointing compared to the International Scale log reduction.  In your case, the International Scale log reduction will probably be a better indicator of overall progress.  Oddly, since the IS uses averaging, you may have been diagnosed with a -1 log reduction before ever taking any TKI drugs (just estimating for the purpose of explanation).

The "funny feeling" in your throat you describe is likely soft tissue edema (swelling) from the Sprycel which squeezes on the esophagus.  All the TKI drugs can do that, but Sprycel may be the biggest offender.  You may also feel it in the ear canals.

I like your lupinus texensis avatar.


#4 Antilogical


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Posted 09 February 2013 - 03:35 PM

Hey, thanks, Trey - I forgot to ask the doc about my inner ears during my last appointment, and you have just given me the explanation of what's happening.  Appreciate the info!

Dx: Sudden severe anemia detected 07/2011, followed by WBC spike. CML Dx 02/2012.

Rx: 03/2012-Gleevec400.  Reduced 02/2013 to Gleevec300 due to side effects (low blood counts).

Response: PCR-Und within 7 mo. on G400. Maintained MMR4-MMR4.5 on G300. PCR-Und since 02/2016.

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