Prognostic value of whole-body metabolic tumour volume and total lesion glycolysis measured on ¹⁸F-FDG PET/CT in patients with extranodal NK/T-cell lymphoma

Purpose: The aim of this study was to determine whether maximum standardized uptake value (SUVmax), whole-body metabolic tumour volume (WBMTV), and whole-body total lesion glycolysis (WBTLG) measured on pretreatment ¹⁸F-FDG PET/CT can predict prognosis in patients with extranodal natural killer/T-cell lymphoma (ENKTL). Methods: We conducted a retrospective analysis of 20 patients with newly-diagnosed ENKTL who underwent pretreatment ¹⁸F-FDG PET/CT. WBMTV and WBTLG were measured automatically using the boundaries of voxels presenting SUV > 3.0. Uni- and multivariate analyses for survival and disease progression were performed using clinical variables and PET parameters (SUVmax, WBMTV, and WBTLG). Results: During the follow-up period (median 26.3 months), 12 patients showed disease progression and 10 patients died from the disease. Receiver operating characteristic curve analysis showed cut-off values for SUVmax, WBMTV and WBTLG of 8.1, 14.4 cm³ and 52.7, respectively. Univariate analysis showed that the International Prognostic Index (IPI) score and PET parameters were significant predictors of overall survival (OS) and progression-free survival (PFS). Multivariate analysis, even after adjustment for the IPI score, showed that high WBMTV was the best predictor of OS and PFS, and high SUVmax and WBTLG were significant predictors of PFS. Conclusion: Our results suggested that the use of PET parameters together with the IPI score may be useful for detailed prediction of prognosis in ENKTL patients. Therefore, despite a lower IPI score, patients with high PET parameter values might be considered candidates for aggressive therapy to improve clinical outcomes.