I am curious to learn from my CMLers what their “undectable” status could mean. It really depends on the sensitivity of the test that your lab uses for the pcr.
I have been “detected but too low to quantify at less than 0.002%IS” for 2 years now. Interestingly, during these 2 years, I was taking Sprycel 100mg, then 50mg and then 0mg....
So I would like to know what was the last pcr number did you have before your first “undetected” status??
Than you for your help. 😁
It's been seven years since my Dx and my last PCR was the first reported to be below the LOD (limit of detection). Here are my PCR scores from the last couple of years. Albeit my pathologist qualified his report with the quote below. I guess he wants to make sure I don't stop taking my meds?
2018 000.233%, 000.013%, 000.007%, 000.006%
2019 000.007%, 000.007%, none detected at limit of 0.0069% - "However, very weak qualitative amplification is still seen"
Any PCR measure less than 0.01% is indistinguishable with "undetected". It is in the noise of the test and can easily be a false positive or error. Many labs do not report values below 0.01% as anything other than "not detected". Other labs use a fixed value of 0.0069. Going out 4 decimal places is incorrect numerically. The precision is just not there.
For perspective - I have been "undetected" now for over two years. M.D. Anderson only reports PCR levels to two decimal places. It's quite possible I have plenty of bcr-abl still in my system - but it is at such a low level it is "undetected". In other words, if the precision of the PCR test was greatly improved and I was tested by this "new" system, my PCR could be: 0.0000000345 % What does that mean? I'm no longer "undetected".
We know that current technology indicates undetected patients have around a million CML cells moving about under the radar (sort of speak). And yet, when we stop treatment, CML does not return for half of us up to and including patients who test at around 0.1%.
Despite having bcr-abl, our bodies are doing something to keep CML in check through our immune system. That is, in my opinion, the key feature of successful TFR. One has to get their CML burden low enough (i.e. < 0.01%) in order for their immune system to take over. It's like having a bug infestation. Stepping on them is not a solution until you only have one or two left.
Also - do I believe every human being has bcr-abl cells? Yes, you bet. Everyone has bcr-abl. Just so low and managed that it never becomes disease. Why we got it is just bad karma and low vitamin D !
Yes.
My reports have shown only X.XX% if PCR falls below 0.01% then the report showed PCR < 0.01%.
No third or other decimal places. It simply is erroneous to do so and can get people anxious.
for example. If your PCR went from 0.000043 to 0.000086 - doubling!! you would become nervous, but it means NOTHING. As it is, 0.1% is a very very very low residual disease. You can't even see CML cells under the microscope until PCR is above 1%. Each decimal place movement to the left is an order of magnitude (factor of 10) reduction in molecular signature of bcr-abl. This is huge.
To repeat - 0.00X is beyond the limits of the assay.
But you know that there are on the market, tests that are way more sensitive than 0.01%. For example, my lab is sensitive to MR4.7 or 0.002% and below that, they just say detected but below quantification.
In the case of MD Anderson, they should not say “undetected” but should say Complete Molecular Remission below MR4 or something like that.
I understand that for the progression of the disease, there is no difference between MR4 (0.01%) and MR4.7 (0.002%). Actually, it seems that MR3 (0.1%) is already safe haven for the disease and the life expectancy is already so close to “normal” people.
I like that my test can detect lower than MR4 so I can see a trend earlier than 0.01%.
Ditto Karinne. Johns Hopkins went to a more sensitive test about 2 years ago and its limit of detection is 0.002. I take that to mean they are confident of accuracy up to that point. If it were lower, it would say something like "detected, but below the limits of this test." (Before the new test, it would say like yours, Scuba, <0.01.) My onc says if it's ever undetected, it'll say, "undetected." Anyway, just got another one at 0.005 which is the same number for the past 18 months. Weird. In terms of safety they may be equivalent - thank goodness! - but detected is still detected and I'm afraid I can't get comfortable calling myself undetected. Yet.
Scuba,
I think I understand you saying <0.01 is equivalent to “undetectable.”....
So, in my case (0.0083), my PCR would be equivalent to undetectable (?) right?
My doc uses a lab that detects down to 0.0069, and I was thinking I need to find another lab that goes deeper. But maybe not (?).
Sarah, at these really low levels the repeatability of the PCR process has quite a wide scatter. Processes vary; if your actual level is 0.0083% the test results could be anywhere between about 0.012% and 0.0041%. (i.e +/- 50% of the measured value). Scuba's absolutely correct point here is that it doesn't matter; you are well below the MMR level below which CML is under control. Key thing to keep an eye on is the trend in results more than say 3 or 4 consecutive results all trending upwards might be an issue, but results varying up and down in the third decimal place when the first two are zeros do not give an indication of any change in your condition.
Undetectable is not something I think it is useful to aim for - there was some recent research to show that the some of the general public have a level of BCR-ABL which is detectable with modern tests; that does not mean they have CML.
