Magnetic Resonance Imaging-Guided Radiotherapy Delivery Systems for Cancer Treatment: A Review of Clinical Effectiveness, Cost-Effectiveness and Guidelines

In Canada, cancer is the leading cause of death, comprising 30% of all death events. ¹ Radiation therapy is a common treatment option used in approximately two-thirds of all cancer patients, ² and can be used on its own or in combination with chemotherapy and/or surgery. ^{1 , 3} Image-guided radiotherapy facilitates tracking the location of the tumour and surrounding organs, and may result in less radiation treatment-related morbidity for patients compared those without image-guided radiotherapy. ⁴ While using computed tomography (CT) for image-guided radiotherapy is the current standard of care, the field of radiation oncology is constantly evolving with the emergence of new technologies for cancer treatment. ^{5 , 6} In 2017, the first magnetic resonance imaging-guided radiotherapy (MRgRT) delivery system was approved by Health Canada. ⁷ MRgRT delivery systems combine a linear accelerator system and a magnetic resonance imaging (MRI) scanner into one therapeutic device. ^{6 , 8} MRgRT delivery systems enable “cross-sectional, beam-on imaging,”(p.1058) which aids in monitoring motion of the tumour and organs at risk (OAR) while delivering radiotherapy treatment. ⁶ Compared to CT, MRI has superior tissue contrast resolution providing improved visibility of soft issues and has less motion blurring issues because a slice of MR data can be acquired in a fraction of a second. ^{6 , 9} This is particularly important for target areas susceptible to respiratory motion and bowel motility. ⁶ Given that MRgRT requires significant health care resources (e.g., financial, physical space to house the delivery system), ¹⁰ there is a need to determine whether MRgRT may offer a more clinical and cost-effective form of treatment for purchasing decisions by health care decision-makers. Ultimately, the feasibility of novel MRgRT delivery systems as a standard of care for patients with cancer will depend on its clinical and cost-effectiveness compared to other cancer treatments. The aim of this report is to summarize the evidence regarding the clinical and cost-effectiveness, as well as guidelines for the use of MRgRT delivery systems for the treatment of patients with cancer requiring radiotherapy.
(Copyright © 2019 Canadian Agency for Drugs and Technologies in Health.)