Safety of low-dose radiotherapy in newly diagnosed stage I/II extranodal NK/T-cell lymphoma: a single-center retrospective analysis

This study aimed to investigate the feasibility and safety of low-dose radiotherapy (RT) (< 50 Gy) in patients with stage I/II Extranodal NK/T-cell lymphoma (ENKTCL). Clinical and treatment data from 158 stage I/II ENKTCL patients who received combined chemoradiotherapy at the First Affiliated Hospital of Zhengzhou University from 2020 to 2022 were retrospectively analyzed to compare locoregional control (LC) and survival outcomes between high-dose (≥ 50 Gy) and low-dose (< 50 Gy) RT groups. All patients achieved an objective response (OR) after treatment, with a median follow-up of 51 months. The 5-year overall survival (OS) and progression-free survival (PFS) rates were 90.1% and 81.7% in the high-dose group (n = 130), compared to 84.0% and 68.2% in the low-dose group (n = 28), with no significant statistical differences between the two groups. Notably, no local recurrence was observed in the low-dose group (100% local control rate), and the incidence of grade ≥ 3 RT-related adverse events (AEs) was significantly lower in the low-dose group than in the high-dose group. Preliminary evidence suggests that for newly diagnosed stage I/II ENKTCL patients receiving combined chemoradiotherapy, low-dose radiotherapy may not compromise LC and survival outcomes while reducing the incidence of grade 3-4 adverse events, with 40-45 Gy appearing to be the optimal dose range within the examined parameters.