Plasma EBV-DNA and peripheral blood mononuclear cell EBV-DNA have disparate clinical relevance in patients with extranodal NK/T-cell lymphoma

•PBMC EBV-DNA poorly correlated with imaging-based disease assessment and plasma EBV-DNA in patients with ENKTCL, while Plasma EBV-DNA strongly correlated with disease status.•Plasma EBV-DNA was more sensitive than PET/CT and CT/MRI in response evaluation and relapse monitoring. Regardless of imaging-based assessment, a substantial increase of plasma EBV-DNA indicated disease progression during treatment, and relapse was almost inevitable in patients with positive plasma EBV-DNA at the end of treatment.•When imaging-based disease assessment was discordant with plasma EBV-based assessment, the kinetic patterns of EBV-DNA were helpful to identify at-risk patients. Relapse occurred only in patient with intermittently or persistently positive plasma EBV-DNA, and occasionally positive EBV-DNA did not correlate with relapse.