Magnetic Resonance-Guided Stereotactic Body Radiotherapy of Liver Tumors: Initial Clinical Experience and Patient-Reported Outcomes

Abstract

Purpose/ObjectiveStereotactic body radiation therapy (SBRT) has emerged as a valid treatment alternative for non-resectable liver metastases or hepatocellular carcinomas (HCC). Magnetic resonance (MR) guided SBRT has a high potential of further improving treatment quality, allowing for higher, tumoricidal irradiation doses whilst simultaneously sparing organs at risk. However, data on treatment outcome and patient acceptance is still limited.Material/MethodsWe performed a subgroup analysis of an ongoing prospective observational study comprising patients with liver metastases or HCC. Patients were treated with ablative MR-guided SBRT at the MRIdian Linac in the Department of Radiation Oncology at Heidelberg University Hospital between January 2019 and February 2020. Local control (LC) and overall survival (OS) analysis was performed using the Kaplan–Meier method. An in-house designed patient-reported outcome questionnaire was used to measure patients’ experience with the MR-Linac treatment. Toxicity was evaluated using the Common Terminology Criteria for Adverse Events (CTCAE v. 5.0).ResultsTwenty patients (with n = 18 metastases; n = 2 HCC) received MR-guided SBRT for in total 26 malignant liver lesions. Median biologically effective dose (BED at α/β = 10) was 105.0 Gy (range: 67.2–112.5 Gy) and median planning target volume was 57.20 ml (range: 17.4–445.0 ml). Median treatment time was 39.0 min (range: 26.0–67.0 min). At 1-year, LC was 88.1% and OS was 84.0%. Grade I° gastrointestinal toxicity °occurred in 30.0% and grade II° in 5.0% of the patients with no grade III° or higher toxicity. Overall treatment experience was rated positively, with items scoring MR-Linac staff’s performance and items concerning the breath hold process being among the top positively rated elements. Worst scored items were treatment duration, positioning and low temperature.ConclusionMR-guided SBRT of liver tumors is a well-tolerated and well-accepted treatment modality. Initial results are promising with excellent local control and only mildest toxicity. However, prospective studies are warranted to truly assess the potential of MR-guided liver SBRT and to identify which patients profit most from this new versatile technology.

Clinical adoption patterns of 0.35 Tesla MR-guided radiation therapy in Europe and Asia

“…Lastly, outcomes data linked to this dataset was unavailable. However, peer-reviewed evidence on clinical outcomes for 0.35T-MRgRT with or without oART in both prospective and retrospective series continues to grow [ 4 – 20 ]. Ongoing and completed prospective trials awaiting maturation of outcomes data will provide additional insights in the coming years.…”

“…Despite eight years of clinical use, MRgRT is still generally considered a novel technology, and optimal clinical applications continue to be investigated. However, a growing body of prospective and retrospectively collected data on clinical outcomes for some difficult-to-treat cancers has become available [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. While a number of users has reported on the clinical use of MRgRT, the general pattern of utilization of these systems in Europe and Asia has not been reported [21][22][23].…”

“…19 Afdeling for Kraeftbehandling, Herlev og Gentofte Hospital, Herlev, Denmark. 20 Radiation Oncology, Chungnam National University Sejong Hospital, Daejeon, Republic of Korea. 21 Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea.…”

Patterns of utilization and clinical adoption of 0.35 Tesla MR-guided radiation therapy in the United States – Understanding the transition to adaptive, ultra-hypofractionated treatments

“…Lastly, while the patterns of care provide insights into how end users are applying this technology in the real world, we are limited by the lack of outcomes data directly tied to this dataset and the identified trends in UHfx and adaptive therapy usage. However, reports on clinical outcomes for MRIdian with or without adaptive therapy in both prospective and retrospective series continue to grow [13] , [39] , [40] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , and completed and ongoing prospective trials will provide additional insights. (NCT03621644, NCT04331041, NCT04247165, NCT04162665, NCT04242342, NCT04020276, NCT04915508, NCT04384770, NCT04402151, NCT04422132, NCT03541850, NCT03916419, NCT03936478, NCT03612648, NCT03878485, NCT03972072, NCT04376502, NCT04115254, NCT04368702).…”

Emergence of MR-Linac in Radiation Oncology: Successes and Challenges of Riding on the MRgRT Bandwagon

“…Weykamp et al [ 54 ], using the 0.3 T system for MR-Linac for hepatocellular carcinoma, showed that 5-fraction hypofractionation was well-tolerable with minimum toxicity with 2 years of overall survival of 82%, which is an impressive outcome. For oligometastatic cases arising from breast cancer, Tan et al [ 55 ] showed better outcomes with minimal toxicity, as reported by the patients.…”