Role of pretreatment 18F-FDG PET/CT parameters in predicting outcome of non-endemic EBV DNA-related nasopharyngeal cancer (NPC) patients treated with IMRT and chemotherapy

Purpose: To evaluate the prognostic role of pretreatment 18F-FDG PET/CT metabolic parameters in non-endemic Epstein–Barr Virus (EBV DNA)-related nasopharyngeal cancer (NPC) patients treated with curative intensity-modulated radiation therapy (IMRT) with or without chemotherapy (CHT). Materials/methods: We retrospectively reviewed clinical data of 160 consecutive non-metastatic NPC patients who received IMRT with or without CHT. Forty-nine out of 160 patients that underwent whole body 18F-FDG PET/CT at our institution for disease staging with a minimum follow-up to 12 months were included in this study. We evaluated the relationship between maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), metabolic tumor volume and total lesion glycolysis (TLG) of primary tumor and cervical lymph nodes with disease-free survival (DFS) and overall survival (OS). We also investigated the prognostic role of clinical variables such as age, disease stage, plasma EBV DNA load (copies/ml), gross tumor volume of primary tumor and lymph nodes. Results: Median follow-up was 55 months. Two- and 5-year OS were 95.8% and 90.5%, respectively, while DFS was 83.4% at both time points. SUVmax of primary tumor ≥ 18.8 g/ml and primary tumor TLG ≥ 203.1 g were significant prognostic factors of worse OS. Furthermore, stages IVB and EBV DNA load ≥ 3493 copies/ml were significantly associated with lower DFS. No correlation was found between PET parameters and plasma EBV DNA load. Conclusion: Even in a limited series, our data suggested that SUVmax, SUVmean and TLG of primary tumor could predict a poor outcome in NPC patients also in non-endemic area hypothesizing their use for refinement of prognostication.