Does biodegradable peri-rectal spacer mitigate treatment toxicities in radiation therapy for localised prostate cancer-a systematic review and meta-analysis.

Introduction: There is an increasing use of biodegradable peri-rectal spacer prior to radiation therapy for prostate cancer to reduce treatment-associated rectal toxicity. While data from individual trials and cohorts is maturing, there is a lack of an updated quantitative analysis that includes outcomes following peri-rectal spacer. We aim to delineate the clinical impact of peri-rectal spacer in localised prostate cancer patients treated with radiotherapy.

Methods: In March 2024, a systematic search was performed on MEDLINE, Embase, and Cochrane Central Register of controlled trials for publications since the year 2010. Prospective and retrospective studies reporting comparative outcomes of patients with and without peri-rectal spacer prior to radiotherapy were considered. Outcomes are reported in binary fashion. Random effect meta-analysis with the use of weighted mean difference was adopted. Early (≤3 months) and late rectal toxicity stratified according to the Common Terminology Criteria for Adverse Events (CTCAE) criteria, early and late genitourinary toxicity, quality of life in bowel, sexual and urinary domains (in terms of minimal clinically important difference) were assessed.

Results: The systematic review included 17 studies. There are 3 RCTs, 3 prospective cohorts, and 11 retrospective cohorts. Three thousand two hundred patients were included, with 1471 patients who received peri-rectal spacer and 1729 without. The use of spacer is associated with lower likelihood of late (1.62% vs. 9.35%, RR = 0.25, 95% CI = 0.15-0.42, P < 0.001) and early grade 2 or above late rectal toxicity (3.07% vs. 6.05%, RR = 0.53, 95% CI = 0.33-0.86, P < 0.001). No difference is observed in significant grade 3 or above GI (acute or late) events. There is no statistical difference in bowel-related bowel QoL (risk difference = -0.16, 95% CI = -0.38-0.06, P = 0.15). The perirectal spacer is not associated with negative impact to urinary or sexual domains of QoL either.

Conclusion: In localised prostate cancer patients treated with radiation therapy, the use of peri-rectal spacer is associated with reduced rectal toxicities.