6 replies to this topic

[Sneezy12]

On 4-28-09,at GenPath Labs, my FISH was 96.3% and my bcr/abl was 19.81%. This was apparentlly BEFORE they converted to the International Scale. On 7-20-09, nearly 3 months later AFTER they had converted to the International Scale, my values were FISH 0.5%, and my bcr/abl value was 1.48%. The report then says "The BCR/ABL1 Quant. comparison with International Scale (IS) is 0.89, e.g. BCR/ABL1 value x 0.89 = International Scale ratio. Major Molecular Response, or a 3-log reduction from a standardized baseline, represents a transcript level below 0.112% with this assay. Undetected transcripts represent a 4 log or greater improvement." Can someone please interpret these results! I do not know how to calculate the log reduction. Thank you. Frank

[Trey]

First, FISH is not affected by International Scale.  The FISH is a straight percentage of leukemic WBCs found in the sample, and is between 0 and 100%.  So your FISH has gone from near 100% to near zero -- probably only found one cell out of several hundred (could even be a false positive reading, since FISH does not have .5% accuracy).  So your FISH is very good news.  It essentially shows Complete Cytogenetic Response (CCR).

Regarding your PCR, GenPath says that its conversion factor for converting their PCR numbers to International Scale is .89, and their example shows that you should take the raw PCR value and multiply it by  .89 to convert to the International Scale value.  But that does not make sense to me, and it even seems backward, since the International Scale number for GenPath would then be less than the raw number, which I have not seen anywhere else.  But using their numbers for conversion to International Scale, they say your PCR number would be 1.48% x .89 = 1.32%   If that is accurate (I would question it), then you would apply the standard International Scale log reduction to that number as follows (these log reductions are the standardized part of the International Scale):

International Scale Log Reductions for PCR Values:

100 = zero log reduction

10.0 = 1 log reduction

1.0 = 2 log reduction

.1 = 3 log reduction

So your 1.32% PCR as it was converted to International Scale is just slightly less than a 2 log reduction (again, assuming the conversion information is accurate).  A roughly 2 log reduction is consistent with Complete Cytogenetic Response (CCR).

The classic way to look at this is that your first PCR done 3 months ago at diagnosis was 19.81% (before starting Gleevec), and now the raw PCR number is 1.48%.  So your individual log reduction goals would be as follows: 19.81% = zero log reduction; 1.981 = 1 log reduction; .1981 = 2 log reduction, and .01981 = 3 log reduction

So your 1.48% raw PCR number would be approx 1.2 log reduction for you using your own PCR starting value.  Many do not have a PCR done at diagnosis, so do not have an individual starting point for log reductions.

Personally, I view individual response as shown by long term decreasing raw PCR values as the best indicator of progress.  Using that indicator, you are making good progress at the 3 month point, and it seems that you can claim a CCR response.

[Sneezy12]

Thank you, Trey! Frank

[Sneezy12]

Trey, I telephoned James Weisberger M.D., BioReference (GenPath) Lab Director ( Tel. 800-627-1479 )  and was told the 0.89 conversion factor to the Int. Scale is correct. Frank

[Sneezy12]

Trey, Someone looked at the above results, and told me "If their 3 log reduction value is 0.112% that would mean that their baseline newly diagnosed patient is 112%. Therefore, my log reduction would be 1.88 log based on my current bcr of 1.48%". How does that fit with my original bcr of 19.81% before G was begun? Thanks again! Frank

[Trey]

That is accurate.  112% x .89 = 100% (approx).  The 112% is the GenPath average starting PCR based on its own averaged results for all newly diagnosed patients.  So your starting value of 19.81% was close to 1 log below the average starting (diagnosis) PCR processed at GenPath.   You said your WBC was not very high at diagnosis (about 25K).  So that tracks.  But that average log reduction does not tell you anything about your actual progress on drug therapy.  Who cares what other people's PCR was at diagnosis?  It is your individual response that is important.  You seem to be responding well.  But if someone else started at diagnosis with a PCR value 1 log below the lab average, then did not respond to drug therapy very well, what good is that -- maybe a consolation prize?  That is why I still like to look at individual progress based on individual PCR results compared in sequence (from the same lab) as the best indictor of response.

[Sneezy12]

Trey- Once again thank you for your lucid and very helpful explanation! Frank