Technological advances in radiation oncology are oriented towards improving treatment precision and tumor control. Among these advances, magnetic-resonance-image-guided radiation therapy (MRgRT) stands out, with technological advances to deliver targeted treatments adapted to a tumor’s anatomy on the day while minimizing incidental exposure to organs at risk, offering an unprecedented therapeutic advantage compared to X-ray-based IGRT delivery systems. This new technology changes the traditional workflow in radiation oncology and requires an evolution in team coordination to administer more precise treatments. Once implemented, it paves the way for newer indication for radiation therapy to safely deliver higher doses than ever before, with better preservation of healthy tissues to optimize patient outcomes. In this narrative review, we assess the technical aspects of the novel linear accelerators that can deliver MRgRT and summarize the available published experience to date, focusing on oncological results and future challenges.

Spinal metastasis may occur in 40–70% of patients with cancer. Symptoms can vary from pain to spinal cord compression (SCC) and can affect their quality of life (QoL). Stereotactic body radiotherapy (SBRT) allows dose escalation of spinal tumor metastases, minimizing doses to organs at risk and improving pain control. The aim of this study is to retrospectively describe our institution’s experience with robotic SBRT (CyberKnife^®, Accuray Incorporated, Sunnyvale, CA, USA) for spinal metastases, in terms of feasibility, oncological results, toxicities, and pain relief observed. In total, 25 patients with 43 lesions were assessed, most of them with dorsal metastases (48.8%). The median total dose was 27 Gy (16–35 Gy), the median number of fractions administered was 3 (1–5), and the median dose per fraction was 9 Gy. Pain was evaluated using the visual analogue scale at baseline and at the end of treatment. The statistically significant reduction in pain (p < 0.01) was associated with the total dose of radiotherapy delivered (p < 0.01). Only one patient developed grade 3 dermatitis. Female gender, adenocarcinoma tumors, and lack of previous surgery were associated with better response to SBRT (p < 0.05). Robotic spine SBRT is feasible, well-tolerated, and improves patients’ QoL through a statistically significant reduction in pain, so it should be offered to patients at an early stage in their process.

This observational, descriptive, longitudinal, and prospective basket-type study (Registry #5289) prospectively evaluated the feasibility and acute toxicity of hypo-fractionated radiotherapy on the first 0.35T MR-LINAC in Spain. A total of 37 patients were included between August and December 2023, primarily with prostate tumors (59.46%), followed by pancreatic tumors (32.44%). Treatment regimens typically involved extreme hypo-fractionated radiotherapy, with precise dose delivery verified through quality assurance measures. Acute toxicity assessment at treatment completion revealed manageable cystitis, with one case persisting at the three-month follow-up. Gastrointestinal toxicity was minimal. For pancreatic tumors, daily adaptation of organ-at-risk (OAR) and gross tumor volume (GTV) was practiced, with median doses to OAR within acceptable limits. Three patients experienced gastrointestinal toxicity, mainly nausea. Overall, the study demonstrates the feasibility and safety of extreme hypo-fractionated radiotherapy on a 0.35T MR-LINAC, especially for challenging anatomical sites like prostate and pancreatic tumors. These findings support the feasibility of MR-LINAC-based radiotherapy in delivering precise treatments with minimal toxicity, highlighting its potential for optimizing cancer treatment strategies.

Background/Objectives: In Spain, pancreatic ductal adenocarcinoma (PDAC) is the seventh leading cause of cancer-related death, with only 20% of patients eligible for surgery at diagnosis. For the remaining majority, prognosis is poor and effective non-surgical strategies are needed. Stereotactic MR-guided adaptive radiotherapy (SMART) may facilitate the delivery of ablative doses of radiation safely with low toxicity. This study reports the first national experience in Spain with SMART for patients with borderline resectable (BRPC) or locally advanced pancreatic cancer and evaluates its feasibility, safety, and early clinical outcomes. Methods: A prospective observational study was conducted including 28 patients with histologically confirmed BRPC or LAPC treated between August 2023 and December 2024. All patients received induction chemotherapy—mainly FOLFIRINOX (57.1%)—followed by SMART delivered in five fractions (40–50 Gy) using a 0.35T MR-guided linear accelerator. Daily online adaptive recontouring and replanning were performed for all 140 treatment fractions. Toxicities were assessed using CTCAE v5.0, and survival outcomes were estimated using Kaplan–Meier analysis. Results: The median patient age was 67 years, and 71.4% of tumors were located in the pancreatic head. At a median follow-up of 7.4 months after SMART (12.25 months from diagnosis), 6-month local progression-free survival (LPFS) was 89.3% from the start of SMART and 82.1% from diagnosis. Distant progression-free survival (DPFS) at 6 and 12 months was 92.9% and 68.2%, respectively. Median progression-free survival (PFS) was 11.5 months, and the median treatment-free interval was 5.7 months. Median overall survival (OS) was not reached; 6- and 12-month OS rates were 89.3% and 74.1%, respectively. Treatment-related toxicity was limited to grade 2 abdominal pain in 14.3% of patients, with no grade ≥3 adverse events attributed to SMART. Conclusions: SMART is a feasible and safe treatment modality for BRPC and LAPC in real-world clinical practice. These encouraging early outcomes support further clinical investigation and broader implementation.

Background and ObjectivesMR-guided radiotherapy (MRgRT) applied as stereotactic body radiotherapy (SBRT) to the prostate bed represents an emerging post-prostatectomy approach. We report a prospective experience with focus on adverse events and patient-reported quality-of-life (QoL) outcomes.Materials and MethodsThirty-one patients with biochemical recurrence after radical prostatectomy received MR-guided adaptive SBRT (32.5 Gy/5 fractions, 0.35 T MRIdian®). Elective nodal irradiation (25 Gy, 41.9%) and simultaneous integrated boost (35 Gy, 9.7%) were delivered when indicated. Adverse events were graded per CTCAE v5.0; patient-reported outcomes were assessed with EPIC-26 and IPSS.ResultsMedian follow-up was 8.8 months (IQR 6.1–16.8). No grade ≥3 adverse events occurred. Grade ≥2 genitourinary adverse events were 3.3% (1/30) at end-of-treatment and 4.3% (1/23) at 6 months. No grade ≥2 gastrointestinal adverse events were observed beyond the acute phase. EPIC-26 urinary domain scores were preserved (baseline 79.6; 6 months 81.5); bowel scores remained at ceiling throughout. Median PSA declined from 0.31 to 0.02 ng/mL at 6 months.ConclusionsMRgRT-SBRT to the prostate bed demonstrates a favourable early safety profile with preserved patient-reported QoL. Longer follow-up and prospective comparative studies are warranted.

Magnetic resonance-guided radiotherapy (MRgRT) delivered with MR-linac technology represents a major advance in lung cancer radiotherapy, enabling daily online adaptive planning based on high-quality soft-tissue visualization, real-time motion assessment, and anatomy-driven treatment personalization. The challenges in lung cancer treatment with conventional radiotherapy delivery due to respiratory motion, inter and intra-fraction anatomical changes make MRgRT capabilities particularly relevant. This narrative review provides an overview of the current state of the art of MR-guided adaptive radiotherapy in lung cancer, focusing on technical foundations, adaptive workflows, and clinical implementation across different disease stages. Key aspects as patient selection, adaptive decision-making, motion management strategies, and integration into routine clinical practice are discussed. Finally, emerging clinical applications and future directions—including adaptive dose personalization and integration of functional imaging—are outlined, highlighting the potential role of MR-linac–based adaptive radiotherapy as a platform for precision radiotherapy in lung cancer.