The Role of Positron Emission Tomography with 18F-Fluorodeoxyglucose Integrated with Computed Tomography in the Evaluation of Patients with Multiple Myeloma Undergoing Allogeneic Stem Cell Transplantation

Abstract

Positron emission tomography (PET) integrated with computed tomography (PET/CT) has been reported to be useful for screening myelomatous lesions at diagnosis in patients with multiple myeloma (MM) and for monitoring response to autologous stem cell transplantation (auto-SCT). The aim of the study was to evaluate the prognostic significance of PET/CT in MM patients who received allogeneic stem cell transplantation (allo-SCT). Patients who underwent upfront auto-SCT followed by allo-SCT, either as consolidation or salvage treatment, were studied with PET/CT before and/or within 6 months after allo-SCT. The number, the maximum standard uptake value (SUV), and the location (medullary or extramedullary) of focal lesions (FLs) were recorded and investigated as predictors of progression-free survival (PFS) and overall survival (OS) by univariate and multivariate analyses. Fifty-four patients had a PET/CT scan before allo-SCT. Of these, 22 patients (41%) had a negative PET/CT scan, 11 patients (20%) showed 1 to 3 FLs, and 21 patients (39%) had either a diffuse bone marrow involvement or more than 3 FLs. SUV was >4.2 in 21 patients (39%) and extramedullary disease (EMD) was present in 6 patients (11%). Multivariate analysis of prognostic factors before allo-SCT showed that persistence of EMD at transplantation was an independent predictor of poor PFS, whereas OS was negatively influenced by unrelated donor and SUV > 4.2. Fifty-nine patients had a PET/CT scan within 6 months after allo-SCT. Multivariate analysis of post-treatment variables showed that persistence of EMD and failure to obtain complete response or very good partial response after allo-SCT were strongly associated with shorter PFS and OS. Of the 46 patients with evaluable PET/CT scans both before and 6 months after allo-SCT, the 23 patients who maintained or reached a PET complete remission showed a significantly prolonged PFS and OS compared with the 23 patients with persistence of any PET positivity (2-year PFS: 51% versus 25%, P = .03; 2-year OS: 81% versus 47%, P = .001). This study indicates that PET/CT imaging before and after allo-SCT is significantly associated with the outcome, suggesting the utility of this technique for MM staging before allo-SCT and for response monitoring after the transplantation.

Interest of Pet Imaging in Multiple Myeloma

“…Finally, scarce data on the value of FDG-PET before or after allo-SCT are available but two retrospective studies of heavily pre-treated MM patients showed FDG-PET results prior to and after allo-SCT were strongly associated with the outcome (44, 45).…”

Predictive value of 18F‐FDG PET/CT scanning in combination with clinical parameters in patients with newly diagnosed multiple myeloma

“…Zamagni et al recruited 192 MM patients and found that number of FLs > 3, SUVmax > 4.2 and EMD were correlated with shorter OS 3. Most studies showed similar result with Zamagni's work; however, they selected different cut-off values for SUVmax 9,27. For these parameters in solid tumors, there are also no recognized standards to define the cut-off value.…”

Imaging in myeloma with focus on advanced imaging techniques

“…36 ******Other studies have reported that negative FDG PET/CT scans after ASCT are associated with improved PFS. 62,63 In the context of minimal residual disease assessment, there is a clinical need for more sophisticated instruments to measure residual disease as a potential source of relapse. 64 Minimal residual disease assessment has traditionally been performed on bone marrow biopsy, which is limited as it may not assess actual tumour burden.…”