Short-term follow-up results of ultra-low-dose radiotherapy for indolent B-cell lymphoma

Abstract Objective: To evaluate the short-term efficacy and safety of ultra-low-dose radiotherapy (4 Gy) in patients with indolent B-cell lymphoma. Materials and Methods: A retrospective analysis was conducted on 14 patients with indolent B-cell lymphoma treated with ultra-low-dose radiotherapy at our institution from January 2024 to February 2025. All patients received a total dose of 4 Gy delivered in 2 fractions of 2 Gy each. Primary endpoints included response rate, locoregional failure-free survival (LRFS), and progression-free survival (PFS). Results: The median age at diagnosis was 58 years (range, 32–74). Pathological subtypes included 10 cases of follicular lymphoma (71.4%), with tumors located in the tonsils, parotid gland, lumbar vertebra, and various lymph nodes; and 4 cases of mucosa-associated lymphoid tissue (MALT) lymphoma (28.6%), with tumors located in the orbit, stomach, and duodenum. Disease stage was I–II in 11 patients (78.6%) and III–IV in 3 patients (21.4%). At a median follow-up of 12.4 months (range, 5.5–17.6), complete response (CR) was observed in 35.7% of cases (n = 5), partial response (PR) in 42.9% (n = 6), stable disease (SD) in 14.3% (n = 2), and progressive disease (PD) in 7.1% (n = 1). One-year LRFS and PFS rates were 91.7% and 83.9%, respectively. One patient with stage IV follicular lymphoma had a residual local lesion that initially achieved remission after radiotherapy but experienced local progression at 6 months; subsequent targeted therapy restored tumor remission. Another patient with stage II follicular lymphoma achieved local tumor remission but developed lymph node metastases outside the radiation field. No grade 3 or higher treatment-related toxicities were observed. Conclusion: Indolent B-cell lymphoma demonstrates a high remission rate with ultra-low-dose radiotherapy while significantly reducing treatment-related toxicities. Keywords: ultra-low-dose radiotherapy; mucosa-associated lymphoid tissue lymphoma; follicular lymphoma