Blast % in MDS: From TNC or NEC?

[Prashant Sharma]

In what would be a major change from the existing as well as the proposed WHO recommendations, these authors (backed by what they claim is the "largest series of patients with MDS with erythroid hyperplasia") report that calculating the percentage of BM blasts from non-erythroid cells to assign the final category of MDS improves prognostic assessment. It's currently calculated from the total nucleated cells differential (by those who follow the WHO anyway). This better prognostication was true for both erythroid-rich and non-erythroid-rich MDS.

Are we going to switch to NEC blast percentages very soon?

You can read the full article for free here: http://jco.ascopubs.org/content/34/27/3284.long

Prashant Sharma

[Sanjeev Gupta]

Thanks for sharing the article Prashant. I wish to make two points regarding this study:

1. .The message I get from JCO study is to give more weight to the blast % in the prognostication of MDS and probably, this can be done by modifying the prognostic scoring systems (maybe more blast categories & with higher scores) rather than again changing the consensus diagnostic criteria. The current WHO-2016 recommendation about using total marrow cells rather than non-erythroid cells aims at bringing uniformity and more reproducibility of blast % and possibly a step in the right direction

2. The WHO-2016 recommendation of abolishing the Erythroleukemia category and categorizing the cases with >50% erythroid cells with >20% blasts out of NEC (but  <20% blasts of TNC) as MDS has also been backed by studies showing the biological behaviour & genetics of this category similar to MDS rather than AML. The JCO study (based on the 2008 classification) has not included such cases in their study. It would be interesting to check the clinical outcome of the upgraded cases of MDS (based on blast % using NEC) compared to that of Erythroleukemia cases downgraded to MDS (based on blast % using TNC as per 2016 classification).

Regards,

Sanjeev

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Dr Sanjeev Kr Gupta,
MD, DNB, DM (Hematopathology)
Assistant Professor, Lab Oncology,
Room No. 424, Dr BRA IRCH, 

All India Institute of Medical Sciences (AIIMS), 

New Delhi-110029.

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[Prashant Sharma]

Dear Sir and Sanjeev,

WHO 2016 has done away with erythroleukemia, erythroid/myeloid agreed. But that's not the crux of this paper. In fact, that change has made application of their findings easier. Because while these authors start with the cases with >/=50% erythroids, but then they also prove/conclude that its true for every case of MDS (with any % of erythroids).

Basically, its about the blast percentage one gets when the denominator is all cells, versus the higher blast percentage one gets when the denominator is only the non-erythroid cells. What they are saying is that if the same case goes to different categories depending on which blast% you use, then the worse category (always NEC) is BETTER PREDICTIVE of its outcome.

Refining existing prognostic classifications by increasing the no. of blast categories or giving higher scores to blasts (while sticking with the total nucleated cells in the denominator) will not be the same thing Sanjeev, because the blast% obtained from the NEC count is not just DIFFERENT and HIGHER than that from the TNC, but it is UNPREDICTABLY different since every case has a different erythroid %. So its basically a NEW parameter. We can accept it or reject it or wait for confirmatory data, but if what they say is correct (i.e. that the erythroids are just diluting nuisances), then we shouldn't be using TNC blast percentages.

This should be a relatively easy study to do for centres with follow-up data...

Best regards,

Prashant

On Tuesday, 20 September 2016 05:15:46 UTC+5:30, DEEPAK KUMAR MISHRA wrote:

Good discussion indeed. Such morphologic exercises will keep happening even till you have the next one in 2024 or so.

I have personally discussed this with Mario Cazzola, who is one the authors in the Myeloid Group. The way you have been looking at AML-M6 ( pure erythroid / erythroid myeloid ) has changed conceptually. Now no role of NEC and TNC is here to stay. This will reduce inter-observer variability. Mario said many of the MDS's before were labelled as AML-M6 transitioning from MDS in the previous classification.

It is believed the IPSS / WPSS should have another revision. The next International MDS Symposium at Valencia, Spain in May,2017 will discuss this. 

Warm regards.

Dr. Deepak K Mishra

Tata Medical Centre, Kolkata.

On Monday, 19 September 2016 05:53:39 UTC+5:30, Prashant Sharma wrote:

In what would be a major change from the existing as well as the proposed WHO recommendations, these authors (backed by what they claim is the "largest series of patients with MDS with erythroid hyperplasia") report that calculating the percentage of BM blasts from non-erythroid cells to assign the final category of MDS improves prognostic assessment. It's currently calculated from the total nucleated cells differential (by those who follow the WHO anyway). This better prognostication was true for both erythroid-rich and non-erythroid-rich MDS.

Are we going to switch to NEC blast percentages very soon?

You can read the full article for free here: http://jco.ascopubs.org/content/34/27/3284.long

Prashant Sharma

[Sanjeev Gupta]

Dear Prashant,
I agree and understand that blast % calculated using NEC is UNPREDICTABLY different than that obtained using TNC and has been proven useful in better prediction of outcome, at least in MDS. Based on further studies, it may be found useful in other scenarios too.
But, at the cost of being speculative, I wish to add, "What limits the possible utility of upgrading cases into higher categories using NEC criteria is the fact that it has not withstood the test of time, at least in the case of Erythroleukemia".

Regards,
Sanjeev

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