Prognostic Value of Volume-Based Positron Emission Tomography/Computed Tomography in Nasopharyngeal Carcinoma Patients after Comprehensive Therapy

We assessed the prognostic value of standardized uptake value (SUV) and volume-based methods including wholebody metabolic tumor volume (WBMTV) and whole-body total lesion glycolysis (WBTLG) using 18F-fuorodeoxyglucose positron emission tomography/computed tomography (PET/CT) of patients with nasopharyngeal carcinoma (NPC) after therapy. Methods. A total of 221 posttherapy NPC cases were enrolled, all of whom had undergone PET/CT scanning and follow-up in this retrospective study. The diagnostic results of PET/CT were analyzed and compared with histopathological diagnosis or clinical follow-up. Receiver operator characteristic curves, the Kaplan-Meier method, and the log-rank test were used to assess the optimal cutof values for WBMTV and WBTLG to identify independent predictors of survival. Results. The detection rates of the threshold SUV were 2.5, 20%, and 40%, and SUV background methods were 65.6% (378/576), 80.2% (462/576), 71.5% (412/576), and 90.4% (521/576), respectively (p < 0.005). Patients with a WBMTV < 8.10 and/or a WBTLG < 35.58 had signifcantly better 5-year overall survival than those above the cutofs (90.7% versus 51.2%, p < 0.001; 91.7% versus 50.4%, p < 0.001), respectively. Multivariate Cox regression modeling showed both WBTLG (RR, 1.002; p = 0.004) and age (RR, 1.046; p = 0.006) could be used to predict overall survival. WBTLG (RR, 1.003; p < 0.001) may have predictive relevance in estimating disease-free survival. Conclusions. SUV volume-based threshold background methodology had a signifcantly higher detection rate for metastatic lesions. WBTLG could be used as an independent prognostic indicator for posttherapy NPC.