Rectal spacers appear to reduce prostate cancer recurrence risk

In this video, Sean P. Collins, MD, PhD, a radiation oncologist at Tampa General Hospital in Tampa, Florida, discusses a study presented at the 2025 American Society for Radiation Oncology exploring the impact of rectal spacers on biochemical cancer control in prostate cancer patients undergoing radiation therapy.¹ Historically, rectal spacers—introduced in 2016—were primarily used to reduce bowel toxicity and improve quality of life by minimizing rectal side effects such as frequency and urgency. However, Collins emphasized that until now, no study had directly examined whether spacers influence cancer control outcomes.

The research analyzed data from a large, real-world electronic medical record cohort of 36,000 men treated between 2016 and 2022. Among them, approximately 2500 patients received rectal spacers. The study first investigated which patients were most likely to receive spacers and found that men with localized disease, obesity, or diabetes, and those undergoing dose-escalated radiation or brachytherapy boosts, were more likely to have spacers placed. Conversely, men with metastatic disease were less likely to receive them, possibly due to concerns about spreading cancer into the space between the prostate and rectum.

After conducting a matched-pair and multivariate analysis, the team observed that older age and metastatic disease were associated with worse outcomes, as expected. However, the key finding was that men who received rectal spacers had a 50% lower risk of biochemical failure—with a 10% failure rate in non-spacer patients vs 5% in those with spacers.

Collins highlighted that this discovery challenges prior assumptions: 80% of surveyed clinicians believed spacers had no effect on cancer control. The results suggest that well-placed spacers enable safer dose escalation, which is known to improve prostate cancer outcomes. Although not a randomized trial, Collins called the findings hypothesis-generating and encouraging, reinforcing spacers’ dual benefit—enhancing quality of life and potentially improving cancer control.

REFERENCE

1. Collins SP, Tran E, Roane A, Morton R. Real-world data analysis of biochemical recurrence after primary radiotherapy for prostate cancer: Propensity matched comparison of patients with hydrogel rectal spacing vs no spacing. Int J Radiat Oncol Biol Phys. 2025;123(1S):e724-725. Abstract 3599