Why Rectal Spacers Matter in Prostate Radiotherapy: Trends and Techniques

Welcome back to another Urology Times Peers & Perspectives series. In this episode, Daniel Welchons, MD, explains that his practice adopted rectal spacing early, noting that dose escalation and hypofractionation have become standard in prostate radiotherapy, making tools that protect the rectum increasingly important. Aurelie Garant, MD, agrees, citing a body of phase 3 trial evidence supporting hypofractionation and ultrahypofractionation as standard of care, and stresses that shaping dose away from the rectal wall reduces both physician-graded toxicity, such as late gastrointestinal bleeding, and patient-reported symptoms like urgency and cramping.

Turning to mechanism, Welchons describes the basic goal of perirectal spacing as pushing the anterior rectal wall as far from the prostate as possible so the radiation dose gradient spares it. Garant adds that spacers are placed transperineally with the patient's legs raised but treated with legs down, creating a pivoting effect that makes separation at the prostatic apex especially important for achieving adequate dose reduction.

The conversation then compares hyaluronic acid and hydrogel spacer (spaceOAR) products. Welchons explains that hydrogel polymerizes quickly after injection and is difficult to visualize on ultrasound, so physicians largely have to trust placement, whereas the hyaluronic acid spacer Barrigel is pre-polymerized and can be visualized and adjusted in real time, allowing physicians to confirm symmetry and coverage as they go. Garant notes this visibility gives physicians more time to be deliberate and makes Barrigel notably more forgiving for residents and fellows still learning the transperineal approach, a technique that is increasingly relevant as transperineal biopsy adoption grows.

In the next episode, "Rectal Spacer Evidence: Acute Toxicity, Durability, and Safety," Welchons and Garant walk through the pivotal trial data and long-term outcomes behind hyaluronic acid spacers, including how their safety profile holds up in real-world practice.