Purpose: To evaluate radiotherapy (RT) and chemotherapy (CT) treatments of early-stage extranodal natural killer/T-cell lymphoma (ENKTL). Materials and Methods: Fifty-five patients with stage I or II ENKTL [n=39 (71%) and 16 (29%) patients, respectively] who were treated with RT between 1999 and 2013 were analyzed retrospectively. The median age was 54 years (range, 24–81). Patients were grouped by treatment modality as RT alone [n=19 (35%)], upfront CT plus RT [CT+RT, n=16 (29%)], and concurrent chemoradiotherapy [CCRT, n=20 (36%)]. The median RT dose was 48 Gy. Patient characteristics between each treatment group were well balanced. Patterns of failure and survival were analyzed. Results: The overall response rate after RT was 94.6%. Ten patients experienced distant failure, and seven experienced local failure comprising five in-field and two out-field failures. The local and distant failure rates in the RT-alone group were the same (16%). In the CT+RT group, the most common failure sites were local (19%). In the CCRT group, the most common failures were distant (25%). At a median follow-up of 56 months (range, 1–178 months), the 5-year overall survival (OS) and progression-free survival rates were 66% and 54%, respectively. The 5-year OS rate for the RT-alone and CT+RT groups were 76% and 69%, respectively, and the 2-year OS rate for the CCRT group was 62% (p=0.388). Conclusion: In the era of multimodal treatment for ENKTL, RT alone using advanced techniques should be considered for local disease control, whereas maintenance CT regimens should be considered for distant disease control.
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