Medullary Abnormalities in Appendicular Skeletons Detected With ¹⁸F-FDG PET/CT Predict an Unfavorable Prognosis in Newly Diagnosed Multiple Myeloma Patients With High-Risk Factors.

Abstract

<b>OBJECTIVE.</b> The prognostic value of medullary abnormalities in the appendicular skeleton (AS) of patients with multiple myeloma (MM) has recently been suggested. However, functional evaluation of these abnormalities using PET/CT has not been investigated to date. This study aimed to explore the prevalence and prognostic relevance of AS medullary abnormalities depicted by PET/CT in patients with MM. <b>MATERIALS AND METHODS.</b> This retrospective study included 228 consecutive patients with newly diagnosed, symptomatic MM who were treated with novel agents. All patients underwent pretreatment ¹⁸F-FDG PET/CT. <b>RESULTS.</b> There were 157 (68.9%) patients with zero AS focal lesions, 33 (14.5%) with one to three AS focal lesions, and 38 (16.7%) with more than three AS focal lesions on pre-treatment PET/CT. Patients with more than three AS focal lesions showed significantly shorter progression-free survival (PFS) and overall survival (OS) than did those with fewer lesions (both, <i>p</i> < 0.001). In multivariate analysis, the presence of more than three AS focal lesions remained prognostic for both PFS and OS (both, <i>p</i> < 0.001). Furthermore, the presence of more than three AS focal lesions discriminated patients with both significantly shorter PFS and significantly shorter OS even among patients with established high-risk parameters, including high-risk cytogenetic abnormalities, advanced disease stage, and established high-risk PET/CT findings. <b>CONCLUSION.</b> The presence of more than three focal lesions in the AS on pretreatment PET/CT was an independent predictor of poor survival in patients with newly diagnosed MM. Remarkably, this finding discriminated patients with shorter survival from among those with established high-risk factors. Evaluation of findings in the AS may complement and improve the prognostic performance of known stratification systems as well as PET/CT.