Diagnosed with SMM, SPB, or MGUS?

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When Should MGUS Patients Have a Bone Marrow Biopsy?

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The answer to the question “when should MGUS patients have a bone marrow biopsy” (BMB) depends on the patient’s risk tolerance. Does the newly diagnosed MGUS patient want to fully understand their health situation? Does that desire, or not, to know fully, mean that the patient is willing to undergo a certain amount of discomfort?

My point in listing all these statistics is to point out that the presence of plasma cells in the bone marrow can be a tricky thing. And people, especially those diagnosed with MGUS, may or may not want to know their plasma cell specifics.

When I was diagnosed with multiple myeloma in 1994, a pathologist told me that I had MM.  My oncologist told me that I had a single plasmacytoma of bone (SPB).

A bone marrow biopsy may have determined my actual diagnosis.

What diagnostic tests should MGUS patients undergo?

  1. Blood tests:
    • Complete Blood Count (CBC): To check for abnormalities in blood cell counts.
    • Serum protein electrophoresis (SPEP): To detect the presence of abnormal proteins in the blood.
    • Serum immunofixation electrophoresis (IFE): To further characterize the abnormal proteins detected in SPEP.
  2. Urine tests:
    • Urine protein electrophoresis (UPEP): To detect and characterize abnormal proteins in the urine.
  3. Imaging studies:
    • Skeletal survey: X-rays of the bones to check for any bone lesions or fractures, which may indicate progression to multiple myeloma.
    • MRI or CT scans: These imaging studies may be done to assess for any organ damage or lytic bone lesions.
  4. Bone marrow biopsy: To examine the bone marrow for the presence of abnormal plasma cells, which are characteristic of MGUS.
  5. Other tests:
    • Serum free light chain assay (FLC): Measures the levels of free light chains in the blood, which can be elevated in MGUS and can be useful in monitoring disease progression.
    • Kidney function tests: Since MGUS can sometimes lead to kidney damage due to excess protein production, tests such as serum creatinine and estimated glomerular filtration rate (eGFR) may be performed to assess kidney function.

There are certainly MGUS patients who will welcome the article linked below that discusses prediction modeling for MGUS patients. Lots of people simply don’t like the idea of a needle being stuck into one of their bones.

At the same time, there is no better way of determining both pre-MM and full MM specifics other than the full compliment of diagnostic testing listed above.

My experience is that the answer to the question “when should MGUS patients have a BMB” is ASAP. Meaning, a diagnosis of MGUS isn’t accomplished if a bone marrow biopsy hasn’t been done.

Have you been diagnosed with pre-myeloma? Meaning a

  • single plasmacytoma of bone (SPB)
  • monoclonal gammopathy of undetermined significance (MGUS) or
  • smoldering multiple myeloma (SMM)

If you would like to learn more about evidence-based therapies to reduce your risk of a diagnosis of multiple myeloma email me at David.PeopleBeatingCancer@gmail.com

Hang in there,

David Emerson

  • MM Survivor
  • MM Cancer Coach
  • Director PeopleBeatingCancer

A Model for Managing Patients with Monoclonal Gammopathy of Undetermined Significance

A new prediction model indicates which patients with MGUS should be considered for bone marrow sampling.

When should bone marrow sampling be performed in patients with monoclonal gammopathy of undetermined significance (MGUS)? Currently, algorithmic approaches based on a Mayo Clinic model are used widely (Blood 2005; 106:812), but researchers in Iceland now propose an alternative model based on their iStopMM study.

About 1000 people (median age, 68) with presumed MGUS underwent bone marrow sampling; those with the IgM isotype were excluded. The researchers developed a multivariable model to predict ≥10% plasma cells — indicating a diagnosis of smoldering multiple myeloma — on bone marrow examination. The model incorporated MGUS isotype (i.e., IgG, IgA, light chain, or biclonal), monoclonal protein concentration, free light chain ratio, and total concentrations of IgG, IgA, and IgM.

The model’s performance for predicting ≥10% plasma cells in bone marrow was as follows:

  • Sensitivity was 86% (14% of cases were missed).
  • Specificity was 67% (33% of patients with <10% plasma cells were incorrectly predicted to have ≥10%).
  • Specificity was substantially better than that of the Mayo Clinic model, applied to this cohort (67% vs. 41%); sensitivities were similar in the two models.
  • Assuming a goal of identifying patients with ≥10% plasma cells, this model would have allowed deferral of bone marrow sampling in 59% of patients in this cohort (compared with 37% using the Mayo Clinic model).

Development of a Multivariable Model to Predict the Need for Bone Marrow Sampling in Persons With Monoclonal Gammopathy of Undetermined Significance: A Cohort Study Nested in a Clinical Trial

“Conclusion: This accurate prediction model for SMM or worse was developed in a population-based cohort of persons with presumed MGUS and may be used to defer bone marrow sampling and referral to hematology.

Eythorsson E et al. Development of a multivariable model to predict the need for bone marrow sampling in persons with monoclonal gammopathy of undetermined significance: A cohort study nested in a clinical trial. Ann Intern Med 2024 Apr; 177:449. (https://doi.org/10.7326/M23-2540)

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