The LDR BURST trial: a randomised controlled trial comparing the side effects of low-dose-rate brachytherapy against ultra-hypofractionated radiotherapy using spacer gel treatment in men with Cambridge Prognostic Groups 1-3 prostate cancer.

[INTRODUCTION] Long-term follow-up after low-dose rate brachytherapy and ultra-fractionated radiotherapy for localised prostate cancer has demonstrated impressive survival statistics with low toxicity profiles. Superiority between the two treatments has not been shown, with a lack of randomised data comparing the two. Emerging studies have shown a benefit of adding a rectal spacer gel to sit between the prostate and anterior rectal wall to further reduce toxicity following radiotherapeutic treatments. Further randomised studies are, however, recommended to support this data. To the best of our knowledge, the LDR BURST Trial is the first randomised controlled study to compare the toxicity and survival outcomes of low dose rate (LDR) brachytherapy against ultra-hypofractionated external beam radiotherapy with a spacer gel in situ.

[METHODS AND ANALYSIS] This parallel group interventional study sets out to randomise 220 participants with Cambridge Prognostic Groups 1-3 prostate cancer to either LDR brachytherapy with a rectal spacer gel versus external five fraction ultra-fractionated radiotherapy (total dose 36.25 Gy) on a 1:1 basis. The primary outcome is detection of a minimally important difference using the validated Expanded Prostate Index Composite 26 (EPIC-26) questionnaire. Secondary outcomes include further validated patient-reported questionnaires, physician-reported adverse events and survival outcomes.

[ETHICS AND DISSEMINATION] The LDR BURST study has received Health Research Authority (HRA) and Health and Care Research Wales (HCRW) approval (reference 25/LO/047). All participants will provide informed consent prior to participation. Findings from this study will be disseminated through presentations at national and international conferences and publication in peer-reviewed journals.

[TRIAL REGISTRATION NUMBER] NCT07210502.