SpaceOAR Hydrogel spacer for reducing radiation toxicity during radiotherapy for prostate cancer. A systematic review.

Abstract

OBJECTIVE\nTo evaluate the association between SpaceOAR and radiation dosing, toxicity and quality-of-life versus no spacer across all radiotherapy modalities for prostate cancer.\n\n\nMETHODS\nA systematic search of the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase was performed from database inception through May 2020. Two reviewers independently screened titles/abstracts and full papers. Data extraction was performed, and quality assessed by one reviewer and checked by a second, using a third reviewer as required. . The synthesis was narrative.\n\n\nRESULTS\n19 studies (3,622 patients) were included (only one randomised controlled trial, in image-guided intensity-modulated radiotherapy (IG-IMRT), 18 comparative non-randomised controlled trials in external-beam radiotherapy (EBRT), brachytherapy and combinations thereof). No hypofractionation studies were found. Regardless of radiotherapy type, SpaceOAR significantly reduced rectal radiation dose (e.g., V40 average difference -6.1% in high dose-rate brachytherapy plus IG-IMRT to -9.1% in IG-IMRT) and reduced gastrointestinal and genitourinary toxicities (e.g., late gastrointestinal toxicity 1% versus 6% (p=0.01), late genitourinary toxicity of 15% versus 32% (p<0.001) in stereotactic body radiotherapy). Improvements were observed in most Expanded Prostate Cancer Index Composite quality-of-life domains (e.g., bowel function score decrease at 3 and 6 months: average change of zero versus -6.25 and -3.57 respectively in low dose-rate brachytherapy plus EBRT).\n\n\nCONCLUSIONS\nThe randomised controlled trial in IG-IMRT demonstrated that SpaceOAR reduces rectal radiation dose and late gastrointestinal and genitourinary toxicities, with urinary, bowel and sexual quality-of-life improvement. These advantages were verified in observational studies in various radiotherapy types. Further research is required in hypofractionation.