Use of magnetic resonance imaging-guided radiotherapy for breast cancer: a scoping review protocol

Imaging for Radiation Planning in Breast Cancer

Radiation therapy is an integral component of the treatment of breast cancer. The indications and type of radiation therapy vary depending on disease invasiveness and stage. Imaging is the cornerstone for radiation therapy planning. While conventional imaging with CT remains the primary modality for radiation treatment planning locally in the breast, molecular imaging with [¹⁸F]FDG-PET/CT identifies additional occult disease that may help alter the local radiation therapy plan or treat oligometastatic disease. The ultimate effects on long-term outcomes remain to be determined. This article reviews the role of imaging in radiation planning for breast cancer.

Use of magnetic resonance image-guided radiotherapy for breast cancer: a scoping review

In recent years, we have seen the integration of magnetic resonance imaging (MRI) simulators into radiotherapy centres and the emergence MR linear accelerators (MR-linac). Currently, there are limited studies to demonstrate the clinical effectiveness of MRI guided radiotherapy (MRIgRT) treatment for breast cancer patients. The objective of this scoping review was to identify and map the existing evidence surrounding the clinical implementation of MRIgRT for breast cancer patients. We also identified the challenges and knowledge gaps in the literature. The scoping review was reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) extension for Scoping Reviews reporting guidelines. Titles and abstracts were screened by two independent reviewers. Quantitative and qualitative data were extracted and summarised using thematically organised tables. Results identify that accelerated partial breast irradiation (APBI) is the most common form of treatment for MRIgRT. The presence of the magnet does not affect target coverage or violate organ at risk (OAR) constraints compared to standard radiotherapy methods. Consideration is advised for skin and chest wall (CW) due to the electron return effect (ERE) and areas such as armpit and chin due to the electron stream effect (ESE). Clinically, bolus has been used to protect and prevent unwanted dose in these areas. Overall treatment for APBI on the MR-linac is feasible.