Extranodal natural killer/T-cell lymphoma (ENKTL) is an aggressive disorder with heterogeneous clinical characteristics and poor prognosis. The combined value of baseline serum albumin level and absolute peripheral lymphocyte count showed prognostic information in a variety of malignancies, but its evidence is limited in ENKTL. The purpose of this study is to evaluate the impact of prognostic nutritional index (PNI) in ENKTL, and to provide some nutritionally and immunologically relevant information for better risk stratification. We conducted a retrospective study in 533 patients newly diagnosed with ENKTL. The PNI was calculated as albumin (g/L) + 5 × lymphocyte count (109/L). The optimal cutoff values for serum albumin and lymphocyte count were 40.6 g/L and 1.18 × 109/L, respectively, and 47.3 for PNI. After a median follow-up of 70 months, the 5-year overall survival (OS) and progression-free survival (PFS) were 56.2% and 49.5%, respectively. Patients in low PNI group had more unfavorable clinical features, and tended to have worse 5-year OS and PFS compared with those in high PNI group. According PNI-associated prognostic score, patients were classified into different risk groups. Significant difference has been found in 5-year OS and PFS in different risk groups. When PNI and PNI-associated prognostic score were superimposed on the International Prognostic Index (IPI), prognostic index of natural killer lymphoma (PINK), or nomogram-revised risk index (NRI) categories, the PNI and PNI-associated prognostic score provided additional prognostic information. Therefore, PNI and PNI-associated prognostic score could be independent prognostic factors for ENKTL and may be useful for risk stratification and clinical decision-making.
