The role of ¹⁸F-FDG PET/CT metabolic tumour volume in predicting survival in patients with metastatic nasopharyngeal carcinoma

Objectives: To investigate the role of PET-derived imaging markers in predicting metastatic nasopharyngeal carcinoma (NPC) outcomes. Materials and methods: A total of 56 patients with metastatic NPC were enrolled. Before treatment, all of the participants underwent ¹⁸F-FDG PET/CT. The following ¹⁸F-FDG PET parameters were assessed: standardised uptake value, metabolic tumour volume (MTV), and total lesion glycolysis. Multivariate Cox proportional hazards models were used to identify the independent predictors of survival. Results: The multivariate analysis showed that performance status > 1 (P = 0.007), Epstein-Barr virus (EBV) DNA titre > 5000 copies/mL (P = 0.001), and MTV > 110 mL (P = 0.013) were independent risk factors for progression-free survival (PFS). Male sex (P = 0.004), performance status > 1 (P < 0.0001), EBV DNA level > 5000 copies/mL (P < 0.0001), and MTV > 110 mL (P = 0.003) independently predicted overall survival (OS). The 2-year PFS and OS rates of the patients with MTV ≤ 110 mL were 23.2% and 43%, respectively, compared with 0% and 9.1%, respectively, for those with MTV > 110 mL. Combining the MTV with the EBV DNA titre allowed further survival stratification by dividing the patients into three groups with distinct PFS (2-year rates = 30.8%, 7.1%, and 0%, P < 0.0001) and OS (2-year rates = 68.4%, 40%, and 0%, P < 0.0001) rates. Conclusion: The MTV appears to be an independent risk factor in metastatic NPC patients. This factor is complementary to the EBV DNA titre for predicting survival in metastatic NPC.