Potential for focal magnetic resonance-guided stereotactic body radiotherapy for prostate cancer: A review

Abstract

Prostate cancer is the most commonly diagnosed cancer among Australian men. Current whole gland radiotherapy treatment regimens are associated with known toxicities. The MR-Linac has the capability to deliver real-time visually guided radiation to enable focal therapy and reduce toxicity through decreasing radiation doses to organs at risk. This review article discusses the rationale, potential benefits and limitations of the MR-Linac in focal prostate stereotactic body radiotherapy (SBRT), in an effort to reduce toxicity-related side effects for men with low to favourable-intermediate risk prostate cancer. Pubmed was systemically for all published and ongoing trials using the search terms ‘Prostate’ and ‘MRI Linac or MR Linac’. 8 articles were reviewed, of those 1 was deemed relevant, additions were made and expert opinions in the field were sought regarding the most relevant research. Real-time MRI imaging during the delivery of each fraction with daily plan adaption is now a reality due to the development of the MR-Linac system. It is hoped that with improved real-time imaging, treatment accuracy can be improved, increasing the percentage of the planning target volume receiving the prescribed dose while reducing radiation to the surrounding organs at risk. Early results of prostate SBRT are promising but further research is needed into long term survival benefits and toxicity related outcomes. Focal stereotactic radiotherapy for low-risk intermediate prostate cancer using the MR-Linac has the potential to provide adequate tumour control while decreasing the toxicity and quality of life impact of whole gland treatment for men with localised prostate cancer.