Survival trends for extranodal NK/T-cell lymphoma, nasal type from different anatomical sites: a population-based study

BACKGROUND: Extranodal natural killer/T-cell lymphoma (NKTCL), nasal type mostly involves the upper aerodigestive tract (UAT). NKTCLs derived from the UAT are referred to as nasal NKTCLs, while those without UAT involvement are referred to as extra-nasal NKTCLs. In this study, we aimed to investigate the outcomes and survival trends of NKTCLs from different anatomical sites. METHODS: Data from the US Surveillance, Epidemiology, and End Results (SEER) database on NKTCL (diagnosed between 1987 and 2016) were retrospectively analyzed. RESULTS: A total of 714 patients with NKTCL were included. The median overall survival (OS) and cancer-specific survival (CSS) were 36 and 57 months, respectively. For the entire cohort, the OS was improved from era 1 to era 2 with marginal significance (P=0.0595), however, no improvement was shown in CSS. For nasal NKTCLs, the OS of patients from era 2 was significantly improved compared to that of patients from era 1 (P=0.0244). The OS was significantly improved in non-cavity nasal NKTCLs (P=0.031) but not in nasal cavity NKTCLs (P=0.2982). Significant improvements in OS (P=0.0025) and CSS (P=0.0176) were found in stage I/II non-cavity nasal NKTCLs. For patients with extra-nasal NKTCLs, no difference was found in survival outcomes between the 2 eras. CONCLUSIONS: We have demonstrated that the outcomes of non-cavity nasal NKTCLs, especially those in stage I/II, have improved in the new era, while the outcomes of nasal cavity NKTCLs and extra-nasal NKTCLs have not improved. Our study highlights the heterogeneity in clinical outcomes and biology among NKTCLs from different sites. More studies are warranted to define the optimal treatments for patients with NKTCLs.