Risk stratification based on changes in the standard maximal uptake value on PET/CT and the plasma Epstein‒Barr virus (EBV) DNA status after two cycles of chemotherapy for extranodal NK-/T-cell lymphoma.

Although different types of prognostic indices have been applied in extranodal NK-/T-cell lymphoma (ENKTL), they are based mainly on clinical characteristics before treatment. Moreover, these methods lack early assessment and tumor metabolic parameters. It remains unclear whether changes in the plasma Epstein-Barr virus DNA (EBVDNA) status and SUVmax after two cycles of chemotherapy may predict disease prognosis. We retrospectively analyzed the clinical records of 119 patients with ENKTL. According to the multivariate analysis, limited stage (LS), interim EBVDNA (I-EBVDNA) negativity and a ≥ 50% decrease in the sum of the SUVmax for the target lesion (DSSTL) were significantly associated with complete remission after two cycles of chemotherapy (p = 0.005, p = 0.016 and 0.026, respectively). LS disease, I-EBVDNA negativity and ≥ 50% DSSTL were strongly associated with prolonged PFS (HR = 2.953, 95% CI 1.433-6.009, p = 0.003; HR = 2.479, 95% CI 1.239-4.958, p = 0.01; and HR = 2.048, 95% CI 1.037-4.405, p = 0.039, respectively). Based on these predictors of PFS, a preliminary scoring system was developed. Patients with scores of 1 and 2/3 had poorer survival outcomes than those with a score of 0 (HR = 2.030, 95% CI 0.816-5.048, p = 0.044, and HR = 2.377, 95% CI 1.663-3.396, p = 0.000, respectively). This scoring system also applied well to overall survival (OS) and appeared to be superior to the revised Ann Arbor staging system (p < 0.001, vs. p = 0.205). By assessing the early response to chemotherapy, interim changes in the SUVmax and I-EBVDNA could be used to predict disease prognosis and better stratify patients into subgroups with different prognoses of ENKTL. Further prospective studies are needed to verify these findings.