For patients with NK/T-cell lymphoma, plasma EBV-DNA has been found to be a prognostic factor, and those with positive plasma EBV-DNA at the end of treatments are more likely to suffer from disease relapse. The investigators previously reported one-year progression free survival rate of 22.2% for patients with positive plasma EBV-DNA at the end of treatments. Recently, anti-PD-1 antibody has been shown to be highly effective in the treatment of NK/T-cell lymphoma. Thus, this study aims to evaluate the role of maintenance with anti-PD-1 antibody for patients with positive plasma EBV-DNA at the end of treatments.
