How to cite: Davis BJ. Advantages of Prostate Cancer Rectal Spacers. Grand Rounds in Urology. October 23, 2025. Accessed Apr 2026. https://grandroundsinurology.com/advantages-of-prostate-cancer-rectal-spacers/
Summary
Brian J. Davis, MD, PhD, FABS, Professor of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, reviews data on rectal spacing in prostate cancer radiation therapy, focusing on external beam radiation therapy (EBRT), proton stereotactic body radiation therapy (SBRT), and brachytherapy. Dr. Davis presents long-term clinical and dosimetric outcomes derived from a large Mayo Clinic cohort and contextualizes these findings within historical dose-escalation trials. He emphasizes rectal toxicity as a limiting factor in prostate radiation and evaluates rectal spacers as a mitigation strategy.
Dr. Davis presents data from over 1,400 cases of patients with rectal spacers who received proton SBRT and more than 3,500 cases of those who were treated with EBRT. Dosimetric comparisons demonstrate consistent reductions in high-dose rectal exposure when spacers are used. Dr. Davis reviews results from randomized hydrogel spacer trials showing reduced grade 2 or higher gastrointestinal toxicity and improvements in bowel-related quality-of-life metrics. He also compares rectal toxicity outcomes across historical 3D conformal radiation therapy, intensity-modulated radiation therapy, and image-guided radiation therapy trials.
Dr. Davis examines the role of rectal spacing in brachytherapy, including its impact on rectal V100 and the risk of hematochezia. He discusses practical considerations for spacer placement timing during low-dose-rate and high-dose-rate brachytherapy, as well as common misconceptions about spacer use in certain patient groups.
Using case examples, Dr. Davis discusses the benefits of hydrodissection for safety, symmetry, and anatomical confirmation during spacer placement. He reasserts that data illustrating the advantages of rectal spacing supports its use across multiple prostate radiation modalities.
About the 28th Annual Southwest Prostate Cancer Symposium:
Presented by Program Chairs Nelson N. Stone, MD, Richard G. Stock, MD, and William K. Oh, MD, this conference educated attendees about advances in the management of localized and advanced prostate cancer, with a focus on imaging, technology, and training in the related devices. It included a scientific session, as well as live demonstrations of surgical techniques. You can learn more about the conference here.
ABOUT THE AUTHOR
Brian J. Davis, MD, PhD, FABS, is a Professor of Radiation Oncology at Mayo Clinic in Rochester, Minnesota. Dr. Davis also serves as a consultant for the Department of Radiation Oncology and the Department of Physiology & Biomedical Engineering at Mayo Clinic. He specializes in genitourinary cancer, and his research interests include prostate cancer, proton therapy, intensity-modulated radiation therapy, external beam radiotherapy, and brachytherapy.
