Introduction For indolent B-cell non-Hodgkin lymphomas (iNHLs), ultra-low-dose radiation therapy (ULDRT) with 4 Gy has demonstrated durable local control (70%), although distal relapses may occur. Concurrent systemic chemotherapy with radiation therapy (RT) extends progression-free survival (PFS) but is often avoided due to toxicity. We hypothesize that the combination of adaptive ULDRT, with repeat treatment as needed, and single-agent rituximab results in excellent local and systemic control with minimal toxicity. Methods We conducted an institutional review board (IRB)-approved retrospective review of patients with iNHLs (n=26) who were treated with both ULDRT and rituximab (four weekly doses of 375 mg/m2), either concurrently or within a short interval (median 16 days), at our institution from 2017 to 2024. Treatment response and disease control (local and distant) were measured by PET/CT. Overall survival (OS) and PFS were analyzed using the Kaplan-Meier method. Common Terminology Criteria for Adverse Events (CTCAE) v4 was used to record acute and long-term toxicities. Results Overall response rate (ORR) at the first follow-up was 28/31 (90%), of which 19 sites (61%) achieved complete response (CR) and nine (26%) achieved partial response (PR). One (3%) patient had stable disease (SD). In our cohort, the 2-year in-field, out-of-field, and overall PFS rates were 91%, 78%, and 78%, respectively, and OS was 92%. No patient had disease transformation. Discussion The combination of rituximab and ULDRT demonstrates sustained local and distant disease control with minimal side effects in iNHLs.
Lake et al. (2025) studied this question.