MRI-Guided Radiation Therapy for Splenomegaly: Clinical Experiences and Technical Tips

Abstract Introduction Splenomegaly is a common manifestation in chronic lymphoid and myeloid malignancies. While splenectomy is the preferred treatment for symptomatic splenomegaly, it carries significant risks. Radiotherapy (RT) has traditionally been considered a palliative option. This study explores the use of Magnetic Resonance-Guided Radiotherapy (MRgRT) for splenic irradiation (SI) in patients with myelofibrosis (MFI) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN). Methods This single-center retrospective analysis includes patients with MFI and MDS/MPN who underwent MRgRT SI between 2018 and 2022. Ten 1 Gy fractions was delivered to PTV (spleen+5mm margin). An adaptive online/offline strategy has been used to reduce the dose to healthy organs. Dosimetric data and clinical outcomes, including pain relief, gastrointestinal symptoms, and hematological values, were assessed. Results Twelve patients completed SI without interruption, with supportive transfusions as needed for cytopenias. Pain and gastrointestinal symptoms relief was observed in most cases. The mean percentage reduction in spleen volume was 53.61%, with an average cranio-caudal extension reduction of 77.78%. Twenty-nine (24.2%) out of 120 fractions were online adapted and 14 (11.7%) were replanned offline. Non-hematological toxicities were not reported. At a median follow-up of 12.9 months, 6 patients died, while 9 patients underwent hematopoietic cell transplantation, with 6 of them surviving. Conclusion This study demonstrates MRgRT SI feasibility in MFI and MDS/MPN patients, offering symptom relief and significant spleen volume reduction. Real-time setup verification and adaptive planning allowed for tailored treatment with reduced margins, minimizing healthy tissue exposure. Larger prospective studies with longer follow-up are needed to further validate its efficacy and safety.