Reducing Prostate Cancer Radiation Toxicities With Hydrogel Rectal Spacers With Sean Collins, MD

What Are Hydrogel Rectal Spacers?

Hydrogel rectal spacers create approximately a 1-cm separation between the prostate and rectum, to reduce rectal radiation dose during prostate cancer treatment. This seemingly small distance can translate into meaningful reductions in late rectal bleeding and bowel urgency/frequency—side effects that can significantly impact quality of life in older adults who are active and traveling. “My goal as a radiation oncologist is to make sure that for men who choose radiation, they have least side effect burden possible,” Dr. Collins underscores. “I’m glad I have the ability to actually spare the rectum and make sure they don’t have that bothersome side effect.”

Known and Emerging Quality-of-Life Benefits

Historically, spacers have been adopted to lower the rectal radiation dose and improve bowel-related quality of life. Emerging thinking suggests that spacers may enable higher therapeutic doses to the prostate, potentially improving long-term outcomes—especially important as patients are living longer with the disease. “I have a lot of patients who live into their nineties, so when radiating them at 70, we have to control their cancer for 20 years,” Dr. Collins notes. “When younger men get radiation, it’s even more important to give high doses of radiation to the prostate to eradicate the cancer and cure them for the rest of their lives.”

Investigating the Outcomes

Using a large electronic medical record dataset (the Truveta database) of 36,000 men—about 2,000 with spacers—the team explored predictors of spacer use and oncologic outcomes. Spacers were more often used in localized disease, with dose-escalation strategies (eg, brachytherapy), and in men with comorbidities that elevate rectal risk. A propensity-matched analysis compared 250 spacer patients to 500 non-spacer patients, tracking prostate-specific antigen (PSA) nadir and biochemical failure at two years.

While 11% of men without spacing failed treatment, only 5% of men who received spacing failed treatment, suggesting a roughly 50% relative reduction in biochemical failure. Dr. Collins cautions that this is not prospective, randomized evidence but compelling real-world data that should prompt further investigation.

Patient Selection

The findings particularly inform use in patients with localized disease undergoing dose escalation, whether via brachytherapy or a simultaneous integrated boost to a dominant intraprostatic lesion. These scenarios carry higher rectal risk but may yield better tumor control when dosing can be safely intensified. Dr. Collins explains, “When I see a prostate cancer patient now, I say, ‘Hey, this is a relatively young guy with a relatively advanced cancer. I want to give him as much radiation as a I can. I want to give him the best chance of being cured without injuring him. To me, this is a new way of thinking about how to use rectal spacers.”

Next Steps

Dr. Collins frames the work as hypothesis-generating: treat spacers as platforms to optimize safety and enable dose intensification where appropriate. Potential benefits to sexual and bladder function have also been reported in some studies, though they weren’t end points in this analysis and have yet to be confirmed. For young people out there, I think this is evidence that we can always make the world better,” he concludes. “We have to have an open mind; we have to be creative. I think this study shows that when we have a product like the spacer, we really have to think about how to optimize it to help patient care.”

Key Takeaways

• Spacers create space between the prostate and rectum to protect the rectum from radiation dose and help reduce bowel toxicity. They have been found to help reduce bowel, urinary, and sexual complications.
• Real-world data suggest an association with lower biochemical failure in dose-escalation settings.
• In a propensity-matched analysis, 2-year biochemical failure was 5% with spacing vs 11% without.
• Candidates likely to benefit from spacing include patients with localized disease with planned dose escalation (brachytherapy or simultaneous integrated boost to dominant lesions) and those with elevated rectal risk.
• Evidence is observational; randomized or randomized-like real-world datasets with longer follow-up are needed.
• Clinically, consider spacers proactively when aiming for intensified local control while preserving quality of life.

About Dr. Collins

Sean Collins, MD, is a Radiation Oncologist at the University of South Florida, Tampa General Hospital. He specializes in prostate cancer radiation therapy, with expertise in the use of rectal spacers. He has published over 300 peer-reviewed articles and abstracts, and his research focuses on patient-reported outcomes following prostate cancer treatment and determinants of racial disparity in prostate cancer.