Characteristics and Outcome of Extranodal NK/T-Cell Lymphoma in North America: A Retrospective Multi-Institutional Experience

Background: Extranodal natural killer/T-cell lymphoma (ENKTL) is rare and clinicaldata from non-Asian countries are lacking. It is unclear whether outcomes and diseasenatural history is similar to reported Asian series. We assessed characteristics and outcomes of patients with ENKTL from major North American centers. Patients and Methods: We retrospectively identified patients with newly-diagnosedCD56 + ENKTL and studied disease characteristics and clinical outcomes. Results: 121 patients with ENKTL diagnosed between June 1990 and November 2012 were identified. Eighty-three patients (69%) had stage I/II disease and were treatedwith combined modality therapy (CMT) (n=53), chemotherapy alone (CT) (n=14) orradiotherapy alone (RT) (n=16). Thirty-eight patients (31%) had stage III/IV diseaseand were treated with CMT (n=12), CT (n=23), or RT (n=3). The median follow-up forthe entire cohort was 51 months. Patients with stage I/II disease, compared to thosewith stage III/IV disease, had superior 2-year progression free survival (PFS) 43% vs19% (p=0.03) and overall survival (OS) 59% vs 29% (p=0.004). Outcomes were similarfor stage I/II patients who received CMT vs RT alone with 2-year PFS (53% vs 47%;p=0.91) and OS (67% vs 67%; p=0.58). No significant differences in outcomes werenoted based on race/ethnicity. Conclusions: This series represents a large experience of ENKTL treated at several major North American academic centers. Our data are consistent with Asian studies: 1) majority of patients present with early-stage disease; 2) overall poor outcome regardless of race/ethnicity; 3) CMT likely yields favorable outcomes for suitable candidates with early-stage disease.