Work

Real-World Data on Barrigel and SpaceOAR Rectal Spacers in Prostate Cancer Radiation Therapy: A Comparative Analysis

Year: 2025

Type: article

Abstract: Background and Purpose Hydrogel rectal spacers are in widespread and routine clinical use for prostate cancer radiotherapy. Theses spacers separate the prostate from the rectum thereby reducing the radiation dose to the rectum. Two major hydrogels are in use, SpaceOAR and Barrigel, yet there is no real-world data comparing these two. This study aims to compare these gels with respect to quality of insertion and dosimetric outcomes. Materials and methods A multicentre retrospective analysis was performed on all prostate cancer men undergoing radiotherapy from 2017 to 2023. Demographic, radiotherapy, and MRI details were imported for analysis. Each multiparametric MRI was scored on rectal spacing placement by two independent observers. Results 822 patients were included for dosimetric and 605 for quality of insertion analysis. The median SpaceOAR volume (13.80cc) was larger than the median Barrigel volume (5.10 cc) (p<0.01). SpaceOAR was more likely to achieve a higher Spacer Quality Score (SQS) compared to Barrigel (5 fraction OR 6.25, >5 fractions OR 2.16; p<0.01 for both respectively). SpaceOAR achieved lower irradiated rectal volumes for 20 fractions, at v60, v46, v38 and v30 (p<0.01 for all) and 5 fractions, v30 (p=0.04), v20 (p=0.01). After accounting for spacer volume, Barrigel achieved better rectal dosimetric outcomes for 20 fraction patients compared to SpaceOAR for volumes between 6-13cc, v57 (p=0.01), v54 (p=0.01). Higher SQS correlated with improved dosimetric outcomes (p<0.05) while no similar monotonic trend was observed with the Fischer-Valuck (FV) score across evaluated dose levels, including v36 (p=0.10), v32 (p=0.26), and v30 (p=0.45). Incidence of rectal wall infiltration amongst SpaceOAR patients was 7/287 (2.44%) compared to none for Barrigel. Conclusions Real world data shows that SpaceOAR achieves better dosimetry than Barrigel likely due to larger insertion volumes. At similar insertion volumes, Barrigel achieves lower irradiated rectal volumes compared to SpaceOAR. Dosimetric outcomes are more likely impacted by volume rather than symmetry of insertion. The SQS scoring method may have better utility than the FV scoring method for assessing dosimetric outcomes. Our data also finds Barrigel has a lower incidence of RWI compared to SpaceOAR.

Source: Advances in Radiation Oncology

DOI: 10.1016/j.adro.2025.101989