Salvage radiotherapy improves survival in patients with locoregionally relapsed stage IE-IIE extranodal natural killer/T-cell lymphoma, nasal type.

Background: This study aims to retrospectively analyze the salvage treatment outcomes and prognostic factors of patients with early stage locoregionally recurrent (LRR) extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTCL). Methods: Between January 1995 and December 2014, 540 patients with stage IE-IIE ENKTCL received chemotherapy (ChT) and/or radiotherapy (RT) in our hospital, and among these, 56 patients who experienced LRR were included in this study. Salvage treatments included RT alone in 4 patients (7.1%), ChT alone in 30 patients (53.6%), and ChT combined with RT in 22 patients (39.3%). Median RT dose was 50 Gy (range 36-60 Gy). The effect of salvage treatment on overall survival (OS) rate from start of initial treatment (IT) as well as that after recurrence was analyzed. Results: The overall median follow-up time from IT was 35.9 months, with a 3-year OS of 72.7%. The median follow-up time after relapse was 14.8 months, and the 3-year OS after relapse was 57.8%. Compared to ChT alone (n=30), treatment with salvage RT (n=26) improved the OS from IT (p=0.040) and after relapse (p=0.009); further, re-irradiation improved the OS from IT (p=0.018) and after relapse (p=0.019). Acute and late toxicities after re-irradiation were mostly grades 1-2 (84.3%). At both univariate and multivariate analyses, better Karnofsky Performance Score (KPS), RT in IT, and RT in salvage treatment were found to be significant factors influencing OS after recurrence. Conclusion: Salvage RT improved survival in patients with LRR stage IE-IIE ENKTCL, and the treatment toxicity was acceptable.