Magnetic resonance-guided stereotactic body radiotherapy (MRIgSBRT) for nodal disease in oligometastatic setting: a...

We evaluated the feasibility and clinical outcomes of MRIgSBRT for nodal recurrence in the oligometastatic disease (OMD) setting, focusing on per-lesion outcomes and prognostic factors. We collected clinical and dosimetric data from a retrospective single-center cohort of patients treated with a 0.35 T MRIgSBRT for nodal recurrences. Endpoints included the 1-year progression-free survival (PFS), local progression-free survival (LPFS), and 3-year overall survival (OS) rate from recurrence. Per-lesion Kaplan-Meier and Cox regression assessed clinical, dosimetric, and technical predictors. 71 patients received nodal MRIgSBRT, with a total of 115 treated metastatic lesions. Local control was high: LPFS 95.5% at 12 months and 94.0% at 24/36 months. OS was favorable (100% at 12 months, 97.2% at 24 months, 95.3% at 36 months). Systemic progression drove most events: PFS 52.6% at 12 months and 24.4% at 24 months; median 12.4 months. No clinically relevant acute or late toxicity was observed. On multivariable analysis, BED₁₀ ≥ 70 Gy was independently associated with improved OS. Multiple metastases increased the risk of local failure in univariate analysis (UVA) (HR 6.30, p = 0.027). MRIgSBRT represents a safe and viable treatment option in nodal oligometastatic setting. It provides excellent and durable local control with minimal toxicity. As distant progression remains the main challenge, careful selection in low-burden disease, dose escalation to BED₁₀ ≥ 70 Gy, and thoughtful integration with systemic therapy emerge as key levers to optimize outcomes. Further prospective studies are needed to assess OMD long-term survival and quality of life and to evaluate possible further treatment optimization strategies.