Efficacy of low-dose radiotherapy (2 Gy × 2) in the treatment of marginal zone and mucosa-associated lymphoid tissue lymphomas

OBJECTIVES: To investigate the efficacy of a schedule of low-dose radiotherapy (LDRT) with 4 Gy (2 Gy x 2) in a cohort of unselected MALT or MZL patients. METHODS: We retrospectively collected all patients receiving LDRT, either for cure or palliation, for a stage I-IV histologically proven MALT or MZL between 2016 and 2020. Response to LDRT was evaluated with the Lugano criteria. Local control (LC), distant relapse-free survival (DRFS), progression-free survival (PFS) and overall survival (OS) were stratified for treatment intent (curative vs palliative) and estimated by the Kaplan-Meier product-limit. RESULTS: Among 45 consecutively enrolled patients with a median age of 68 years (range 22-86), 26 (58%) were female. Thirty-one patients (69%) with a stage I-II disease received LDRT as first line therapy and with a curative intent. Overall response rate was 93%, with no significant difference among curative and palliative intent. With a median follow-up of 18 months, LC, DRFS, PFS and OS at 2 years were 93, 92, 76 and 91%, respectively, in the overall population. Patients receiving curative LDRT had a better PFS at 2 years (85% vs 54%, p < 0.01) compared to patients receiving palliative treatment. LDRT was well tolerated in all patients, without any significant acute or chronic side-effect. CONCLUSIONS: LDRT is effective and well tolerated in patients affected with MALT or nodal MZL, achieving high response rates and durable remission at 2 years. ADVANCES IN KNOWLEDGE: This study shows the efficacy of LDRT in the treatment of MALT and MZL.