This Blood study, published on 22 September, combined four measures of disease in 352 people with newly diagnosed multiple myeloma: marrow plasma cell percentage from whole-slide images, whole-body MRI diffusion volume, PET metabolic tumour volume and serum soluble BCMA.
Soluble BCMA had the strongest prognostic association, independent of imaging-defined volume. Clustering produced four phenotypes; patients with high soluble BCMA had similar 12-month progression-free survival whether their tumour volume was high or low. In patients with large but anatomically confined disease and low soluble BCMA, gain of 1q21 lost its prognostic weight, whereas it carried strong weight when soluble BCMA was high.
For haematopathologists, it is a reminder that marrow plasma cell percentage captures only part of disease burden. Soluble BCMA is not a standard staging test, and the phenotype framework needs validation outside this single cohort.
- Report marrow plasma cell percentage knowing it may not reflect overall disease activity.
- Soluble BCMA is a research prognostic marker, not part of standard staging.
- Interpret 1q21 gain in the context of overall disease biology, not in isolation.
- Watch for external validation before this framework enters practice.
Why it matters
Tumour that circulates may matter more than tumour that is large but confined.
Don't overread it
Phenotypes came from unsupervised clustering in one cohort and need external validation.
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