Change of plasma EBV-DNA during treatment. (A) Plasma EBV-DNA levels of patients who attained complete response (CR) decreased after the treatment and became undetectable. Disease recurrence was observed in 1 patient after ttreatment. (B) For patients who could not attain CR, the plasma EBV-DNA remained at high levels or was re-elevated after the treatment. The pretreatment plasma level was significantly lower for responders (A; mean, 2645 copies/mL) than in nonresponders (B; mean, 16 472 copies/mL).