48 replies to this topic

[Tom1278]

Hi everyone,

 

I haven't posted in a while but I thought I'd give an update...

 

The last few months saw some ups and downs with my results, but I just got my last round of PCR results -- and they were so good the doctor is re-running the test just to make sure.

 

In October 2014 (27 months post-diagnosis), I was at a 2.9 log reduction.  At January's test (30 months), it came back at 2.7 log reduction -- disappointing as you can imagine.  So, they ordered a 6 week follow-up and a mutation test, which happened Monday.

 

The mutation test isn't back, but the PCR came back at a 3.8 log reduction!!!  I'm hoping the re-run confirms it.

 

I had been a very slow but steady responder on 400mg Gleevec until that January test, but they kept me on it because my side effects were minimal and being so young (36)  and there's more long-term usage data on Gleevec.

 

3 mo - 0.4 log reduction

6 mo - 1.2

9 mo - 1.3

12 mo - 1.6

15 mo - 2.1

18 mo - 2.4

21 mo - 2.6

24 mo - 2.8

27 mo - 2.9

30 mo - 2.7

31.5 mo - 3.8

 

So, slow and steady apparently can win the race...

 

Tom

 

[Trey]

Your results re-prove several things we see all the time:

 

1) PCR plateaus often occur at the 12 - 24 month time-frame

 

2) Most people are average responders, otherwise there would be no fast or slow ones

 

3) Most mutation tests are often a waste of time (upticks in PCR without simultaneous loss of CCyR)

 

-3.8) Slow and steady wins the race, even though fast and precipitous is more fun

 

But don't be overly concerned if the next PCR is not as low or lower than -3.8; however, if it is you have even more reason for celebration.

[Dom]

Can someone tell me how the log reduction is calculated? Is that log as in logarithm?

[Robyn]

Sorry if off topic. Been on Sprycel 2.5 years. Diagnosed with a wbc of 48. First 3month result was 2.1. Dr. Was thrilled. Then 4.1---3.2---5---4.3---3.2-----PCRU--- I was so relieved and happy. Now today latest result is 3.4. Lab states it as a small tick up as expected---not alarmed. But I'm very alarmed. When will I stop this up and down? Feeling freaked out. I read that once you reach MMR the chances for progression is very low. Is this normal to bounce around as much as this. In August I was at 3.2 again and terrified of a downward trend, then in November I was PCRU , but now in March I am 3.4. This is so drepressing. Foes anyone else have these results?

[rcase13]

Can someone tell me how the log reduction is calculated? Is that log as in logarithm?

Hey one I can answer. Yes it is logarithmic. 100 to 10 would be 1 log drop in PCR. Most PCR test go to 5 log or 0.001

[Trey]

Robyn,

I assume you are providing log reduction PCR results.  You started with an early diagnosis, so started at a low PCR.  Your results in log reductions have been very good so no reason to be concerned.  People often pop in and out of PCRU at first. 

[Robyn]

Thanks Trey. I am almost 2.5 years in. I seem to bounce so far up and down. That is what scares me. I take 100mg Sprycel with hardly a side effect. It is not approved here in Nova Scotia for front line use so it come free every month from Bristol Myers. I just though I had finally reached undetectable and my bouncing would ease off a little not go all the way back to 3.4.

[Trey]

Robyn,

Maybe you don't fully understand the log reduction issue.  You are NOT going from zero to -3.4 log reduction.  PCRU is not zero, it is -4.5 log reduction.  So you are only going from -4.5 to -3.5.  That may still seem like a big jump, but at those small numbers it is not much.

[CML2012]

Log Reduction.... Yes it is a logarithm and since reduction means negative think
log (1/1000) = -3 when they say a 3 log reduction. So for example, I was at 53% at onset CML so a 3 log reduction for me mean 53 * (1/1000) = .053%. I hope that makes mathematical sense :-)

[chrissy778]

I am basically never going to understand it. I have read it and re read it. Trey you could make a Log reduction calculator. You should totally patent that. You are smart enough, I would buy one.

[Robyn]

Sorry maybe I didn't explain well. Or maybe different in Canada? Here anything over a 5 log is undetectable. I started out at 3 months in with a 2.1 log. Then after 3 months jumped up to 4.1---very excited. 3 months later, back to 3.2. Next Pcr test I hit a 5 log. Dr said any higher and I would be undetectable--but 3 months later back down to 4.2, then 3.2 then I finally hit undetectable. 5+. Today my log reduction was again down to 3.4. Dr seats it's a small drop and not concerned but I get so scared to see the numbers going the wrong way and jumping up and down.

[gerry]

Hi Robyn,

it is all about the trend rather than the bounce. I know of people that have bounced in and out of PCRU a couple of times before it settled down, hopefully that will be the same for you.

[PhilB]

What I find startling in Tom's original post is that his Dr ordered a mutation test for a PCR going from 2.9 to 2.7 log.  If we assume that the Dr isn't a drongo then we need to know how it was done to know why he did it.  If he did it on peripheral blood then my guess is he was being nice and doing it to calm you down.  If he did it on a BMB then it's because he hates you.

[chrissy778]

I agree with Phil, a unnecessary bone marrow is not very nice. 

[Robyn]

Thanks Gerry. Guess I've always been a bouncer. It's so unnerving though. Especially by those big jumps although Dr says that they are not really all that big at these levels.

[CML2012]

Ok Chrissy778 I know I can explain the log to you.  A logarithm is another way of writing an exponent.  A standard log is base 10.  So the logarithm equation is   log₁₀ (answer) = exponent.  Therefore when someone refers to a log 3 or 3 log that means 10³  (because the base is 10 and the exponent is 3) which would equal 1000 (answer).  When someone refers to a log 3 reduction that means the 3 is negative so you have 10^-3 = (1/1000).  ( log₁₀ (1/1000) = -3  because the base is 10, the exponent is -3 and the answer is 1/1000). 

How this works for CML is they take your original percentage, like 53%, and compare to where you are now, like .053%,  .053 is 1/1000 of 53 which is a 3 log reduction because if you divide 53 by .053 it equals 1/1000 which is the answer position of the equation log₁₀ (1/1000) = -3.

Now I have read that a log 5 reduction means the chromosome is undetectable, which is true if you think about log₁₀ (1/100000) = -5.  So that means if my original PCR for BCR/ABL was 53% and I make it to a log 5 reduction I am at .00053% because .00053 is 1/10000 of 53.  So basically the lab is doing the math comparison (division)  for you each time when they say you are at a log # reduction.  

  All of you should remember this from Algebra II back in your high school day   

[gerry]

I think I prefer the percentage point PCR test results, doesn't make my brain hurt as much as the log reduction. 

[Billie Murawski]

Ok Chrissy778 I know I can explain the log to you.  A logarithm is another way of writing an exponent.  A standard log is base 10.  So the logarithm equation is   log₁₀ (answer) = exponent.  Therefore when someone refers to a log 3 or 3 log that means 10³  (because the base is 10 and the exponent is 3) which would equal 1000 (answer).  When someone refers to a log 3 reduction that means the 3 is negative so you have 10^-3 = (1/1000).  ( log₁₀ (1/1000) = -3  because the base is 10, the exponent is -3 and the answer is 1/1000). 

How this works for CML is they take your original percentage, like 53%, and compare to where you are now, like .053%,  .053 is 1/1000 of 53 which is a 3 log reduction because if you divide 53 by .053 it equals 1/1000 which is the answer position of the equation log₁₀ (1/1000) = -3.

Now I have read that a log 5 reduction means the chromosome is undetectable, which is true if you think about log₁₀ (1/100000) = -5.  So that means if my original PCR for BCR/ABL was 53% and I make it to a log 5 reduction I am at .00053% because .00053 is 1/10000 of 53.  So basically the lab is doing the math comparison (division)  for you each time when they say you are at a log # reduction.  

  All of you should remember this from Algebra II back in your high school day   

HUH!

[pammartin]

I agree with Gerry & Billie. I do not understand the reduction process and I doubt I ever will.I hear undetectable and the rolling logs just fade away.

[PhilB]

The reason for talking in log reductions is really simple.  The scientists who designed the tests quickly realised that most of the doctors using it are basically hopeless at maths.  They tried getting them to understand fractions.  They tried getting them to understand percentages,  They even tried with ratios and all they got were blank looks and confusion.  Soon the doctors started mixing up the ratios and the percentages and getting the wrong answer which got the scientists really worried.  The scientists therefore commissioned a major research study, which found that they could be 95% confident that a doctor picked at random would be able to count to five*.

 

The engineers then went back to the drawing board to design a measurement system that worked with this limitation.

Phil

 

*It is recommended that you always check the number of fingers on your oncologist's hand just in case.