[Prognostic Value of Interim 18 F-FDG PET/CT in Extranodal NK/T-Cell Lymphoma, Nasal Type].

OBJECTIVE To explore the value of interim 18F-FDG PET/CT in the prognosis of patients with extranodal NK/T-cell lymphoma, nasal type (ENKTL). METHODS Twenty-one patients with ENKTL who were pathologically diagnosed at Shanghai General Hospital of Nanjing Medical University (Shanghai General Hospital) from January 2015 to December 2018 were retrospectively collected, and 18F-FDG PET/CT imaging was performed before and during treatment (3 weeks after 2-4 chemotherapy courses or 6 weeks after radiotherapy). The complete clinical data of the patients were followed up. The progression-free survival (PFS) and overall survival (OS) were analyzed by the Korean prognostic index (KPI), Deauville score (DS) and the maximum standard uptake reduction rate (ΔSUVmax). The independent risk factors affecting survival were evaluated by COX regression. RESULTS After treatment, 11 patients had complete remission (CR), 3 had partial remission (PR), 1 had stable disease (SD), and 6 had disease progression (PD). The CR patients' △SUVmax was significantly higher than non-CR patients ［(66.07±22.33)% vs (36.87±23.28)%, t=2.927, P=0.009］. Calculated from the receiver operating curve (ROC), the optimal cut-off point of ΔSUVmax was 51.45%. The median follow-up time was 32 months. Kaplan-Meier survival analysis showed that KPI, DS and ΔSUVmax had significance in predicting PFS and OS (P<0.05). COX regression analysis showed that DS was an independent risk factor affecting PFS (P<0.05), and KPI and ΔSUVmax were independent risk factors affecting OS (P<0.05). CONCLUSION Interim 18F-FDG PET/CT imaging has some value in the prognostic evaluation of patients with ENKTL.