Local Control in a Retrospective Series of Magnetic Resonance Guided Stereotactic Body Radiation Therapy for...

Image guided stereotactic body radiation therapy (SBRT) serves as a key local treatment for liver metastases. As a next-generation technology, magnetic resonance guided SBRT (MRgRT) offers theoretical advantages over computed tomography guided SBRT for the management of liver metastases. However, clinical evidence regarding the efficacy of MRgRT for colorectal cancer liver metastases (CRLM) remains lacking.

This retrospective study included patients with CRLM who underwent MRgRT at a single institution between September 2021 and December 2023. Local control (L), distant hepatic control, progression-free survival, and overall survival (OS) were estimated using the Kaplan-Meier method and analyzed using statistical software (R and SPSS). Adverse events were graded according to the Common Terminology Criteria for Adverse Events version 5.0.

Overall, 51 targets (planning target volumes) in 49 patients with CRLM were treated with MRgRT. The median lesion diameter was 1.9 cm (range, 0.5-6.4 cm), whereas the median prescribed dose to the gross tumor volume was 57 Gy (range, 48-60 Gy). The median follow-up duration was 20.1 months. Among the 51 targets, 3 experienced local failure. None of the patients developed grade >2 radiation-related toxicity. The LC rates at 12 and 24 months were 93.8% and 86.6%, respectively. The distant hepatic control rates at 12 and 24 months were 52.5% and 49.2%, respectively. The progression-free survival rates at 12 and 24 months were 31.5% and 25.5%, whereas the OS rates at 12 and 24 months were 91.4% and 84.0%, respectively.

MRgRT achieved favorable LC and OS rates in the treatment of CRLM with minimal toxicity, demonstrating its potential for broader clinical application. Further studies with larger sample sizes and long-term follow-up are warranted to validate survival outcomes and assess late-onset toxicities.