Case Report: Outpatient management of rectal infiltration by iodinated polyethylene glycol hydrogel and stabilized hyaluronic acid spacers in patients with prostate cancer.

Prostate cancer is one of the most commonly diagnosed cancers in men worldwide. Radiation therapy is a widely used treatment for prostate cancer, but it carries the risk of adverse effects on adjacent organs such as the rectum. Therefore, to provide additional protection for the rectum during prostate radiation, perirectal spacers are inserted into Denonvilliers' space, the thin fascial layer located behind the prostate gland and in front of the anterior rectal wall. Polyethylene glycol (PEG)-based hydrogels and recently FDA-approved stabilized hyaluronic acid (sHA) spacers have been designed to create a biodegradable space between the prostate and rectum, with each having its own unique characteristics and both having the potential to infiltrate the rectum. We present two clinical cases of rectal infiltration associated with either the insertion of a PEG-based hydrogel or an sHA spacer. Due to the distinct characteristics of the two spacer types, rectal infiltration was managed with either a conservative or definitive approach. With the PEG-based hydrogel, we implemented conservative management with antibiotics and close monitoring. In sharp contrast, for the sHA spacer, we proactively reversed the infiltration with hyaluronidase (Hyal) prior to starting radiation. These cases illustrate the clinical utility of these management approaches and contribute to the growing body of evidence on the management of potential complications associated with perirectal spacers, potentially supporting the use of newer spacer technologies.