Survival of patients by pretreatment EBV-DNA. (A) Overall survival was significantly different among the groups of patients with plasma EBV-DNA undetectable, low level (< 1000 copies/mL) and high level (> 1000 copies/mL). (B) Overall survival was significantly different among the groups of patients with MNC EBV-DNA undetectable, low level (< 100 copies/μg DNA) and high level (> 100 copies/μg DNA).