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

Fabian Weykamp,Philipp Hoegen,Katharina Seidensaal,Sebastian Klüter,Sebastian Regnery,Carolin Rippke,Laila König,Juliane Hörner-Rieber,Stefan A Koerber,Jürgen Debus,Carolin Buchele,Jakob Liermann,C Katharina Spindeldreier

doi:10.3389/fonc.2021.610637

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.

Highlights

AND PURPOSESurgical resection was one of the first local ablative treatment options for selected patients with hepatic oligometastases [1]
Motion management includes the usage of an internal target volume (ITV) concept resulting in larger, unnecessary target volumes which might further harm organs at risk (OAR) [24]
The presented study is a subgroup analysis from a prospective observational trial comprising cancer patients with liver metastases or primary hepatocellular carcinoma (HCC), who were referred to our institution because they were deemed medically or functional inoperable or refused resection

Summary

Introduction

Surgical resection was one of the first local ablative treatment options for selected patients with hepatic oligometastases [1]. Standard image guidance with cone beam CT scans only offers a limited soft tissue contrast impairing differentiation between tumor lesions and surrounding radiosensitive OAR [19]. Advanced motion management strategies comprise gating and tracking of the target lesion: surface-guided (SG) SBRT uses the body surface as a surrogate structure for image guidance including patient positioning, intra-fraction motion monitoring and respiratory gating [25,26,27,28], while the Cyberknife system can track invasively implanted fiducials using frequent noncoplanar X-ray scans [29]. MR-guided radiotherapy has recently become clinically available offering additional superior soft-tissue contrast for precise identification of liver lesions and adjacent OAR. Patient acceptance needs to be evaluated, considering the long treatment time of MR-guided irradiation of the liver, which is further prolonged through online treatment adaptation [31, 32]

Methods

Results

Conclusion