Prognostic analysis of interim 18F-FDG PET/CT in patients with diffuse large B cell lymphoma after one cycle versus two cycles of chemotherapy

Objectives(18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is routinely used in diffuse large B cell lymphoma (DLBCL) for staging, assessment of remission and recurrence, and estimation of therapeutic efficacy. In this study, we aimed to assess the role of an early interim PET/computed tomography (CT) in the evaluation of response in DLBCL.MethodsSixty primary DLBCL patients (31 females) were analyzed. Baseline and follow-up F-18-FDG PET/CT was performed in patients after one cycle (n=30) and two cycles (n=30) of chemotherapy. The SUVmax% was calculated. Patients were additionally evaluated using the conventional Deauville five-point scale (D-5PS) system. Fluorescence in situ hybridization (FISH) was employed to characterize the MYC gene status. We determined the optimum cutoff value of SUVmax% using receiver operating characteristic (ROC) analysis. Kaplan-Meier analysis was applied to test for the influence of prognostic values.ResultsThe optimal cutoff for the prediction of treatment outcome was a SUVmax% of 57% (after one cycle) and 63% (after two cycles); we could not detect a difference in accuracy with respect to a PET scan performed after one cycle and two cycles of chemotherapy (P >0.05). The SUVmax% and the D-5PS (score 5) showed the highest prognostic value compared to a score of 3 and/or 4 (both after one cycle and two cycles). No significant difference in sensitivity, specificity, accuracy, or the area of under the curve (AUC) of SUVmax% and D-5PS (score 5) was observed between PETs performed after one cycle or two cycles of therapy (P >0.05). SUVmax%, D-5PS (score 5), and MYC gene rearrangement correlated significantly (P <0.001).ConclusionInterim F-18-FDG PET/CT after one cycle of chemotherapy is feasible and yields similar predictive results as compared to an interim F-18-FDG PET/CT after two cycles of chemotherapy in patients suffering from DLBCL. The combination of interim F-18-FDG PET/CT with the MYC gene diagnosis might provide increased prognostic value for DLBCL.