Purpose: The prognostic value of FDG PET/CT in extranodal natural killer/T-cell lymphoma (ENKTL) is still controversial. Furthermore, the utility of the Deauville 5-point scale (DS) in ENKTL is uncertain. Therefore, we designed a prospective study to examine the prognostic value of 3 methods of PET/CT analysis (International Harmonization Project [IHP] criteria, DS, and SUV-based assessment).
Patients and methods: Sixty patients with newly diagnosed untreated ENKTL were enrolled. PET/CT evaluation was performed before initial treatment (pretreatment) and midtreatment (interim). Interim PET/CT response was determined based on IHP criteria, DS, and change in FDG uptake (ΔSUVmax). International Harmonization Project criteria, DS, and ΔSUVmax were then examined for the ability to predict progression-free survival (PFS) and overall survival (OS).
Results: Over a median follow-up of 23.5 months, interim PET/CT based on DS and ΔSUVmax were significant predictors of PFS and OS. After multivariate analysis, DS was an independent predictor of PFS (P < 0.001) and OS (P < 0.001). ΔSUVmax was an independent predictor of OS (P = 0.013) but not PFS (P = 0.054) and with a lower accuracy and positive predictive value than DS.
Conclusions: Interim PET/CT analysis with DS predicts unfavorable treatment outcomes of ENKTL patients, whereas interim PET/CT analysis based on IHP criteria and SUV-based assessment have limited prognostic value.