Re-irradiation of adrenal metastases using MR-guided adaptive SABR: A feasible and effective approach in a high-risk population

Re-irradiation of adrenal metastases is challenging due to cumulative dose constraints. We present seven patients treated with MR-guided adaptive stereotactic ablative radiotherapy (SABR), leveraging real-time imaging and on-table adaptation for precise dose delivery (5× 10 Gy or 3× 15 Gy). This first report of ablative-dose MR-guided SABR in re-irradiation demonstrates excellent local control and acceptable toxicity, with six patients progression-free at median 8.6 months and no grade ≥3 events (one grade 2 vertebral fracture, one grade 1 nausea). By providing a non-invasive alternative to surgery or palliative radiotherapy, MR-guided adaptive SABR expands therapeutic options for high-risk patients.