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Quick question on BCR-ABL numbers


I am hoping some one can point me in the right direction. Quick back story

Final diagnosis last week and started Imatinib 

  • I originally had many blood tests along with a BCR-ABL test which yielded blood/ABL ratio 39.8% by multiplex RT -PCR 
  • other numbers from test - Hb 148 WCC 23.4, Plts 428, neuts 17.48

I also had a bone marrow test the day before starting meds to create a baseline.  My questions are 

  • What is a good ratio re BCR-ABL?
  • I am assuming the bone marrow test will be used for the same measurement and then I will have a new test post 3 months to look at a decrease ? 

I have looked through other threads but find it quite confusing! 


Any help appreciated



Hello - Sorry you had to join this forum but you will find a lot of good information.  I use the following (pg. 30) because I am in US but European guidelines are available on this website as well:


3mo - Under 10% (this is a biggy but not as big if you hit it at 6 months)

6mo - 1-10%

12mo - 0.1-1.0%

Beyond 12mo - under 0.1%

Hope this helps.


Hi Mark

The most important thing you're looking for is to be on a downward trend for PCR results. The guidelines for optimum response listed above are pretty much the same both sides of the Atlantic but they are only guidelines. I did not hit < 0.1% until about 18 months into taking imatinib, having plateaued for about 4 months around 0.4%. That didn't worry me because the guidelines didn't exist when that happened 10 years ago. Some people get to 0.1% in under 6 months. Some people get very concerned if they don't hit these guidelines - as long as the long term trend is down towards 0.1% it is OK.

You will see talk on old threads about hares and tortoises in terms of geting to <0.1%. People who get to that level are very unlikely to have serious issues in the longer term.

A lot of people have had upward blips in a single result, probably due to the fact the test variability is comparatively high at low levels. A single PCR result of 0.1% is actually indicating the level is between 0.05% and 0.15%. Two consecutive PCRs with an upward trend or a long plateau will make a consultant think about a change in drugs. There's a nice explanation of some of the terms around the PCR test to measure BCR-ABL levels on this link which is Prof Clark talking at the patient day in Birmingham last year,

Assuming your bone marrow test does not show any unusual mutations you will probably not have another one.

Hope that helps

I had bone marrow taken at diagnosis but the RNA was stored and no test performed. The blood test at diagnosis was Fish only, 92%. I was told that FISH trumps BCR-ABL until  complete cytogenetic response is achieved. 

Hi Mark,

39.8% is at the lower end of a PCR test at diagnosis. I was 321% for example - but it doesn’t really matter as for the purposes of testing and prognostic indicators we are all treated as if we were 100% at diagnosis. PCR testing for CML is logarithmic, so even for you when your test reads 10% (which is where you want to be at 3 months post DX) that would be considered a log (10x) drop, even though you started at 39.8%.

In terms of a “good” result, the terms that are used in the guidelines are “optimal”, “warning”, and “failure”. For you, the goal is to get to 10% at 3 months ... but plenty of us, including me, didn’t achieve that and are doing great many years later! Really what you want to see if a set of results over time that show a downward trend. You will get times when it goes up - we’ve all had that and been freaked out at first - but it’s virtually always a blip and the next result reverts to a downward trend.

For everything you’ve ever wanted to know about CML and testing - including PCR testing - we at CML Support wrote this booklet. It does get quite detailed, but the first few pages should be pretty understandable. Keep reading until it stops making sense!