2858 - Effect of Dose Escalation of Radiotherapy in Relapse/Refractory Non-Hodgkin's Lymphoma Patients

Purpose/Objective(s):

Radiation therapy (RT) can be effective in the peri-transplant setting for relapse/refractory (r/r) non-Hodgkin’s lymphoma (NHL). Yet even with pre-transplant RT, local failure has been observed to be as high as 20% in some instances. To date, there is little data investigating the role of dose-escalation in this setting. The purpose of this study was to examine the benefit of dose-escalated RT for r/r-NHL.

Materials/Methods:

We reviewed 17 r/r Lymphoma patients who underwent dose-escalated RT for 18 lesions between 2023 and 2025. While most patients were planned for chimeric antigen receptor (CAR) T-cell transplantation, not all patients underwent transplant following RT. The most common dose regimen was 27Gy in 3 fractions. Local failure was defined as progression within the planning treatment volume. Overall and progression-free survival were estimated by the Kaplan Meier method.

Results:

Median age was 70 (interquartile range (IQR) 67-73) with a median follow up of 9.5 months (IQR 9-19). Most patients received 27Gy in 3 fractions (76.5%). Median gross tumor volume was 90cc (IQR 22.5-242.6).11 out of 17 patients (64.7%) underwent CAR-T cell transplantation and all except one patient received RT prior to transplantation. The remaining patients were planned for salvage RT alone. At 1 year, no patients developed a local failure. There were 4 (23.5%) regional failures and 2 (11.8%) developed distant metastases. The estimated 1-year PFS and OS were 46.3% and 88.9% respectively. Treatment was well-tolerated, with 35.3% of patients reporting site-specific grade 2 toxicities such as lymphedema and erythema.

Conclusion:

In this retrospective cohort, dose-escalated RT for r/r NHL was well-tolerated and was associated with excellent local control. Dose-escalated may be a viable strategy to improve outcomes in this setting.