Original Article

Correlation of Biochemical and FDG PET/CT Responses Following Induction Therapy in Newly Diagnosed Multiple Myeloma: A Prospective Observational Study

Abstract

Background: Multiple myeloma is a heterogeneous malignancy with patchy bone marrow involvement, often leading to discrepancies between biochemical and imaging-based response assessments. Site-specific bone marrow biopsies may miss focal disease, while FDG PET/CT detects metabolically active lesions, and the two approaches offer complementary prognostic value.

Materials and Methods: This prospective study included 44 newly diagnosed multiple myeloma patients. The primary aim was to assess the correlation between biochemical and PET/CT responses at six months post-induction. A secondary objective was to evaluate the impact of PET/CT response on 12-month event-free survival (EFS).

Results: The median age was 55.5 years. At baseline, more than 3 focal lesions and extramedullary disease (EMD) were observed in 61.4% and 34.1% of patients, respectively. After six months of induction therapy, 86.3% achieved at least a very good partial response (≥VGPR) biochemically, but 52.3% remained PET/CT-positive. Baseline >3 focal lesions and EMD significantly predicted persistent PET/CT positivity (p = 0.004). Notably, 50% of patients with ≥VGPR still showed PET/CT-positive findings. At 12 months, 75% of patients who experienced clinical events had been PET/CT-positive at six months, compared with 47.2% of those without events (p = 0.245). The 12-month event-free survival was lower in the PET/CT-positive group (73.9% vs. 90.4%, p = 0.182), though this difference was not statistically significant.

Conclusion: 18-FDG PET/CT can detect residual disease not captured by biochemical markers, highlighting the value of combined assessment in multiple myeloma. Baseline >3 focal lesions and EMD predicted persistent PET/CT positivity. Although PET/CT positivity at six months showed a trend toward worse 12-month EFS, larger studies are needed to confirm its prognostic significance.

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IssueVol 20 No 2 (2026) QRcode
SectionOriginal Article(s)
Keywords
Multiple myeloma; Biochemical response; FDG PET/CT scan; Focal lesion; Extramedullary
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Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
How to Cite
1.
Sharma H, Kumar P, Nayan N, Kumar R, Seth T, Dhawan R, Dass J, Aggarwal M, Viswanathan G, Chauhan R, Mahapatra M. Correlation of Biochemical and FDG PET/CT Responses Following Induction Therapy in Newly Diagnosed Multiple Myeloma: A Prospective Observational Study. Int J Hematol Oncol Stem Cell Res. 2026;20(2):159-173.