Bone marrow biopsy and/or blood tests for MGUS

Posted by Patty, Volunteer Mentor @pmm, May 10, 2023

Somebody was talking about some new blood test that would eliminate the need for bone marrow biopsy to definitively dx MGUS. I think this is interesting. Any of you bypassing the BMB in favor of these blood tests?

https://www.targetedonc.com/view/new-blood-tests-reduce-need-for-bone-marrow-biopsy-in-multiple-myeloma

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Profile picture for Patty, Volunteer Mentor @pmm

@lpro After conferring with my physicians I have opted not to have a BMB at this time. My numbers are very stable. No invasive medical procedure is without risk. If my numbers reached a threshold of concern, by all means I would agree to have one.
https://www.myeloma.org/videos/do-patients-mgus-always-need-undergo-bone-marrow-test

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I am lost now. I thought the diagnosis of MGUS included a bone marrow with < 10% plasma cells. Can that be confirmed any other way?

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I was diagnosed through a blood test which checked my various protein levels. Showed me with a band 1 abnormal M protein. It was at .7 and been checked two timesc since and will check every 3 months . If it stays stable no need for a bmb.

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Profile picture for lpro @lpro

I am lost now. I thought the diagnosis of MGUS included a bone marrow with < 10% plasma cells. Can that be confirmed any other way?

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Monoclonal gammopathy is, by definition, the presence of a monoclonal immunoglobulin ("M-spike") and/or abnormal free light chains ("FLCs") in blood, urine or both, produced by clonal plasma cells. A sufficiently high M-spike or sufficiently high/low K/L FLC ratio raises the risk level for progression to SMM or MM, and should prompt a BMB - in my case, a very low M-spike, but a K/L ration of effectively 0. If the BMB shows >10% plasma cells, then the diagnosis becomes either SMM or MM, depending on presence of symptoms and/or signs of organ damage. In other words, a BMB is not necessary for a diagnosis of MGUS. This is a very general account; there are multiple levels of complexity.

NB: I am not a physician, although I played one in various contexts (one of which was not television, for those of you who recall the reference) before I retired.

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Profile picture for Patty, Volunteer Mentor @pmm

@lpro After conferring with my physicians I have opted not to have a BMB at this time. My numbers are very stable. No invasive medical procedure is without risk. If my numbers reached a threshold of concern, by all means I would agree to have one.
https://www.myeloma.org/videos/do-patients-mgus-always-need-undergo-bone-marrow-test

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I watched the video at https://www.myeloma.org/videos/do-patients-mgus-always-need-undergo-bone-marrow-test
He talked about this iceland study done by IStopMM team published in 2024. I couldn't find the study anywhere. Can you point me to the study of blood test results to determine if a BMB will be >10%.

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The study you reference is not yet complete, but the abstract of a 2024 interim report is at https://www.acpjournals.org/doi/10.7326/M23-2540

In many cases, it's not clear to me why a study of how blood tests may predict BMB results matters. For anyone in the gray treatment/nontreatment zone - me, for example - BMB results matter a great deal. Of course, any medical procedure has risks, but a BMB is quite safe. I for one would not accept a prediction in place of the actual result.

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Profile picture for wesleym @wesleym

The study you reference is not yet complete, but the abstract of a 2024 interim report is at https://www.acpjournals.org/doi/10.7326/M23-2540

In many cases, it's not clear to me why a study of how blood tests may predict BMB results matters. For anyone in the gray treatment/nontreatment zone - me, for example - BMB results matter a great deal. Of course, any medical procedure has risks, but a BMB is quite safe. I for one would not accept a prediction in place of the actual result.

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Thanks for the link. It appears that the study is using patients: 1043 persons with IgG, IgA, light-chain, and biclonal MGUS detected by screening and an interpretable bone marrow sample.
I have IgM MGUS with levels going up very quickly. I wanted to get a prognosis based on this calculator. https://awmrisk.com/index.html
I already have all the values except the % needed from a BMB. If I had a good way of estimating the BMB results, I would put off having the actual BMB until it was estimated to be over 10%.
I'm now guessing that since the study doesn't include any IgM people, the authors knew it wouldn't be applicable because maybe IgM people are looking at WM rather than MM.

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