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

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncologic Imaging

Background:

• Hydrogel rectal spacers are standard for prostate cancer radiation therapy, separating the prostate from the rectum to minimize rectal radiation dose.
• SpaceOAR and Barrigel are the two primary hydrogels used, but real-world comparative data are limited.

Purpose of the Study:

• To compare SpaceOAR and Barrigel hydrogel rectal spacers in terms of insertion quality and dosimetric outcomes in a real-world setting.

Main Methods:

• A multicenter retrospective analysis of 822 prostate cancer patients undergoing radiation therapy (2017-2023).
• Analysis included demographic, radiation therapy, and MRI data.
• Rectal spacing placement was assessed by two independent observers using multiparametric MRI.

Main Results:

• SpaceOAR had a larger median insertion volume (13.80 cc) than Barrigel (5.10 cc).
• SpaceOAR achieved higher Spacer Quality Scores (SQS) and lower irradiated rectal volumes across multiple dose levels.
• Barrigel demonstrated better rectal dosimetric outcomes than SpaceOAR at similar insertion volumes (6-13 cc) and had a lower incidence of rectal wall infiltration (0% vs 2.44%).

Conclusions:

• SpaceOAR's superior dosimetry is likely attributed to larger insertion volumes.
• Barrigel offers comparable or better dosimetric outcomes at similar volumes and a lower risk of rectal wall infiltration.
• Spacer volume appears to be a more significant factor in dosimetric outcomes than insertion symmetry.