Early-Stage Extranodal NK/T-Cell Lymphoma, Nasal Type: A Role for Elective Nodal Irradiation?

Purpose

Extranodal NK/T-cell lymphoma (ENKTCL) is rare in the Western Hemisphere and is commonly treated with combined modality therapy (CMT).

Methods and Materials

We retrospectively reviewed 35 patients treated with Ann Arbor stage I/II ENKTCL between 1994 and 2015 at a large academic cancer center in the United States.

Results

With 11.6 years median follow-up, median overall survival and progression-free survival were 13.5 and 7.5 years, respectively. Eighteen (51%) patients experienced disease relapse, with 5 regional nodal relapses, of which 2 experienced combined regional and distant relapses. All 5 regional nodal relapses occurred exclusively among patients not treated with elective nodal irradiation (ENI). ENI was associated with improved progression-free survival (hazard ratio [HR], 0.21; 95% CI, 0.09-0.52; P = .018) without significant association with OS (HR, 0.33; 95% CI, 0.11-0.94; P = .11). There was a trend toward improved local control with radiation dose to the primary tumor ≥50 Gy (HR, 0.29; 95% CI, 0.08-1.08; P = .098).

Conclusions

In this Western Hemisphere cohort of early-stage ENKTCL patients treated with CMT, ENI may have a potential clinical benefit, particularly in patients who are treated with non–asparaginase-containing CMT, such as in patients treated with radiation alone, patients treated with less intensive chemotherapy concurrently, or patients who are unable to tolerate intensive chemotherapy.