Barrigel Spacer Injection Technique

Abstract

The combination of intensity modulated radiation therapy (IMRT) and image guidance technique (IGRT) has enhanced the sparing of normal tissue during definitive radiotherapy (RT) for organ-confined prostate cancer, allowing for dose escalation and reduced recurrence rates and toxicities associated with treatment. However, challenges arise as the close proximity of the posterior prostate to the anterior rectal wall often results in high rectal doses that IGRT alone cannot remedy. To address this issue, biodegradable inflatable balloons, polyethylene-glycol (PEG) based hydrogel, and more recently hyaluronic acid (HA), have been employed to improve rectal dose volume histograms by displacing the anterior rectal wall away from the prostate gland. Unlike other spacing products, HA is a sculptable gel that offers benefits including easy customization to the patient's anatomy without the need for hydrodissection and the ability to visualize the spacer throughout the implant procedure. As the HA gel placement can be both assessed and modified during the brief procedure, consistent quality placement is more readily achieved. Meticulous procedural technique is thus necessary to create a significant, symmetrical radioprotective space from prostate base to apex, leading to improved rectal dosimetry. This technical report outlines the specific technique for HA spacer placement which was employed to obtain the excellent patient outcomes recently reported in the Barrigel® IDE trial. These outcomes include a reduction in the volume of rectal tissue receiving the prescribed radiation dose and a significant reduction in the risk of grade 2+ GI toxicities following RT. Consistent spacing was observed throughout the treatment and no unexpected adverse device effects or HA spacer-related adverse events were reported. Overall, HA spacer is easy to use, safe, and allows for sculptable, customized spacing.