A New Prognostic Index for Extranodal Natural Killer/T-Cell Lymphoma: Incorporation of Serum beta-2 Microglobulin to PINK

Purpose Prognostic Index for Natural Killer Lymphoma (PINK) is the most widely accepted prognostic model for patients with extranodal natural killer/T-cell lymphoma (ENKTL) treated with non-anthracycline-based therapy. We aimed to evaluate the prognos-tic implications of serum 13-2 microglobulin (132M) in the context of PINK and proposed a new prognostic model.Materials and Methods A total of 138 patients who were newly diagnosed with ENKTL and treated with non-anthracycline-based chemotherapy were identified. The cut-off value of high serum 132M was calculated by maximal-chi square methods (4.1 mg/L). A new prognostic model incorporating serum 132M into PINK was proposed and validated in an independent validation cohort (n=88).Results The patients' median age was 53.5 years (range, 19 to 80 years). Patients with high serum 132M levels had significantly worse overall survival (OS) and progression-free survival (PFS). In multivariate analysis, high serum 132M was an independent adverse prognostic factor for OS. A new PINK-B (Prognostic Index for Natural Killer Lymphoma-serum 13-2 microglobulin) model stratified patients into three groups with distinct OS and PFS in the training cohort (3-year OS, 84.1% [95% confidence interval, 75.1 to 94.2], 46.8% [36.1 to 60.8] and 17.6% [6.3 to 49.2] for the low-, intermediate, and high-risk groups, respectively; 3-year PFS, 70.6% [59.4 to 83.8], 35.9% [25.9 to 49.8], and 7.35% [1.1 to 46.7] for the low-, intermediate-, and high-risk groups, respectively). The PINK-B model was further validated in an independent cohort.Conclusion Serum 132M is an independent prognostic factor for ENKTL patients. The new serum 132M-based prognostic model may be useful for identifying ultra-high-risk patients, and it can easily be adopted into daily clinical practice.