F-18 FDG PET/CT and F-18 FLT PET/CT as predictors of outcome in patients with multiple myeloma. A pilot study

Objectives: We evaluated the prognostic significance of the combined use of F-18 FDG (FDG) and F-18 FLT (FLT) PET/CT (PET/CT) in patients (pts) with multiple myeloma (MM) suspected relapse after a first line chemotherapy. Methods: twenty-eight patients (57 ± 12 years) underwent both PET/CT scans over 2-4 weeks. Patients were grouped according to imaging results (FDG+/-; FLT+/-) and the findings compared to the event free survival (EFS). Results: five pts had FDG+; FLT+, 8 showed FDG+;FLT-, two had FDG-;FLT + and 13 presented FDG-;FLT-, mostly (87 %) of FDG+;FLT- pts had destructive lytic bone lesions. At Cox regression analysis the FDG PET/CT (HR 4.4, 95 % CI 1.3-15.4, p < 0.05) and FLT PET/CT (HR 5.8, 95 % CI 1.7-19.3, p < 0.01) were predictive of worst prognosis. The Kaplan-Meier analysis showed that FDG and FLT PET/CT independently influenced the survival. FDG-;FLT-patients had better EFS as compared to FDG+; FLT + pts and FDG-;FLT + pts, those of FDG+;FLT- group also had worsened EFS. Conclusions: results from the aggregate use of PET/CT FDG and FLT in MM represent a valuable prognostic indicator for identifying patients at higher risk of undue events and may help to correctly stratify the patients with suspected relapse.