Extranodal natural killer/T-Cell lymphoma: A population-based comparison of sinonasal and extranasal disease.

OBJECTIVES/HYPOTHESIS Extranodal natural killer/T-cell Lymphoma (ENKTL) is a rare, aggressive malignancy that preferentially affects the paranasal region. This study analyzes the demographic, clinicopathologic, incidence, and survival characteristics of sinonasal ENKTL (SN-ENKTL) and extranasal ENKTL (EN-ENKTL) in a comparative fashion. STUDY DESIGN Retrospective analysis. METHODS The Surveillance, Epidemiology, and End Results database was queried; 528 cases were available for frequency and incidence analysis, and 473 for survival analysis. Data were examined according to age, gender, race, histology, the presence of systemic (or B) symptoms, treatment, and Ann Arbor stage. RESULTS Extranasal disease was a poor prognostic factor (hazard ratio [HR] = 1.69, 95% confidence interval [CI] = 1.30-2.19, P < .05). Patients with EN-ENKTL were older (mean 53.8 vs. 49.9 years, P < .05), most were male (72.5% vs. 59.8%, P < .05), and they were more likely to present with stage IIIE/IV disease (38.33% vs. 18.26%, P < .05). B symptoms were present in 38.41% of the EN-ENKTL group (vs. 22.86%, P < .05), and were a poor prognostic factor in this group only (HR = 1.6593, 95% CI = 1.05-2.62, P < .05). Radiation therapy demonstrated a survival advantage among both groups, especially in early stage disease. CONCLUSIONS SN-ENKTL carries a significantly better prognosis than EN-ENKTL, which presents at more advanced stages. Radiation therapy was associated with increased survival in both groups, especially in cases of localized disease. LEVEL OF EVIDENCE 2b.