Space or…

Top Line: Does a hyaluronic acid rectal spacer reduce GI toxicity from hypofractionated prostate radiation?

The Study: SpaceOAR is a polyethylene glycol hydrogel commonly used to displace the anterior rectal wall away from the target volume during prostate radiation. In a randomized trial of 222 patients receiving conventionally fractionated radiation (79.2 Gy in 44 fractions), SpaceOAR reduced late GI toxicity. Hypofractionated RT is increasingly used for intact prostate cancer, but there is a slightly higher rate of GI toxicity than with conventional fractionation. Might a rectal spacer help even more during hypofractionation? In this multicenter, randomized phase 3 trial performed by the same group, 201 patients with low or intermediate risk prostate cancer were randomized to receive hypofractionated radiation (60 Gy in 20 fractions) to the prostate with or without a hyaluronic acid rectal spacer (Barrigel). As with SpaceOAR, Barrigel is injected between Denonvilliers fascia and the anterior rectal wall using TRUS and a transperineal approach. In contrast to SpaceOAR, the hyaluronic acid doesn’t have to be injected during a limited period of time. Therefore, it has the potential for a more customized or personalized injection technique and volume (9-12 cc, median 11.2cc). There were no adverse events attributed to the rectal spacer. The primary endpoint was met with almost all (98.5%) patients having a >25% reduction in the rectum V54 compared to their baseline pre-spacer planning CT. The mean reduction in rectum V54 was 85%. More importantly, patients in the rectal spacer arm had a significantly lower rate of acute grade 2+ GI toxicity (2.9% v 13.8%). Barrigel has received FDA 501(k) clearance by the FDA. 

TBL: Barrigel is a hyaluronic acid rectal spacer that reduces acute GI toxicity from moderately hypofractionated prostate radiation. | Mariados, JAMA Oncol 2023