Prognostic value of pretreatment 18F-FDG PET/CT imaging metabolic parameters in patients with early-stage extranodal natural killer/T cell lymphoma

Abstract

Objective To investigate the prognostic value of metabolic parameters calculated from pretreatment 18F-fluorodeoxyglucose (FDG) PET/CT images in patients with extranodal natural killer/T cell lymphoma (ENKTL) of stage Ⅰ-Ⅱ. Methods From August 2010 to April 2018, 67 patients with ENKTL of stage Ⅰ-Ⅱ disease (47 males, 20 females; median age 57 years) in the First Affiliated Hospital of Nanjing Medical University were enrolled, and the clinic data and pretreatment 18F-FDG PET/CT imaging data were retrospectively analyzed. Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of tumor tissue were calculated from PET/CT images with the threshold value of 40% of maximum standardized uptake value (SUVmax). The optimal cut-off values of progression-free survival (PFS) and overall survival (OS) of SUVmax, MTV and TLG were investigated by using receiver operating characteristic (ROC) curve analysis. Kaplan-Meier method, log-rank test and Cox proportional hazards model were used for data analysis. Results SUVmax, MTV and TLG of 67 patients were 12.32(8.65, 16.96), 13.13(7.37, 22.74) ml, 92.17(46.54, 198.46), respectively. ROC curve analysis showed that the cut-off values of SUVmax, MTV and TLG were 13.09, 18.05 ml and 152.81, respectively. Univariate analysis showed that B symptoms, lactate dehydrogenase (LDH) level, β2-microglobulin, Eastern Cooperative Oncology Group (ECOG) score, Korean prognostic index (KPI), SUVmax, MTV, TLG and treatment mode (chemotherapy or chemoradiotherapy) were relative factors affecting PFS (χ2: 5.466-27.163, all P 0.05). Multivariate analysis showed that ECOG score, MTV and TLG were independent prognostic predictors of PFS (relative ratio (RR): 5.107-6.802, all P<0.05), and ECOG score, MTV, TLG and treatment mode were independent prognostic predictors of OS (RR: 0.221-9.106, all P<0.05). Conclusions MTV and TLG from pretreatment 18F-FDG PET/CT images are independent prognostic factors for PFS and OS in patients with ENKTL of stage Ⅰ-Ⅱ. MTV and TLG may be more useful than SUVmax for prognosis. Key words: Lymphoma, extranodal NK-T cell; Positron-emission tomography; Tomography, X-ray computed; Deoxyglucose