Michael J. Zelefsky, MD, presented “Role for Rectal Spacer in the Radiotherapeutic Management of Prostate Cancer” during the 24th Annual Southwest Prostate Cancer Symposium on April 14, 2019 in Scottsdale, Arizona.

How to cite: Zelefsky, Michael J. “Role for Rectal Spacer in the Radiotherapeutic Management of Prostate Cancer” April 14, 2019. Accessed Jun 2024. https://grandroundsinurology.com/role-for-rectal-spacer-in-the-radiotherapeutic-management-of-prostate-cancer/

Role for Rectal Spacer in the Radiotherapeutic Management of Prostate Cancer – Summary:

Michael J. Zelefsky, MD, examines the clinical issue of rectal toxicity in prostate cancer patients treated with prostate radiotherapy. He reviews the current findings on the efficacy of rectal spacers in reducing rectal, gastrointestinal, and genitourinary toxicities in these patients. 


Randomized trials of moderate hypo-fractionated external beam radiation therapy (EBRT), including CHHiP, HYPRO, PROFIT, and RTOG 0415, have shown that rectal toxicity is still a clinical issue for patients undergoing radiation therapy for prostate cancer. Furthermore, ongoing trials evaluating ultra-hypofractionated stereotactic body radiation therapy (SBRT) are predicted to show similar or higher rates of rectal bleeding than the aforementioned trials. A possible solution to reducing this adverse effect and improving patient’s quality of life (QOL) is the application of rectal spacers.

A phase III randomized trial measured QOL, toxicity, and rectal dose in patients treated with conventionally fractionated EBRT using either fiducial markers alone or fiducial markers and a hydrogel spacer. The hydrogel spacer group experienced a significant reduction of rectal exposure.

Initially, the difference in rectal toxicity was negligible, but after three years, there was a significant benefit seen in the rectal spacer patients. Interestingly, this trial demonstrated that the spacers provided better prevention of urinary incontinence as compared to the control. This phenomenon merits further investigation.

In an accruing Phase I-II dose escalation study at Memorial Sloan Kettering Cancer Center (MSKCC), a total of 551 prostate cancer patients received dose-escalated SBRT (40 Gy over 5 fractions). 269 of the 551 patients received a hydrogel spacer. A significant benefit for gastrointestinal and genitourinary toxicities was found.

In conclusion, rectal spacers, along with careful planning, add another enhancement to deliver radiation with a greater degree of conformality. The routine use of rectal spacers with radiation therapy can minimize toxicity, as well as potentially reduce the incidence of secondary cancers in these patients.

About the Southwest Prostate Cancer Symposium

The Southwest Prostate Cancer Symposium (SPCS) is a multi-day conference that seeks to educate urologists, radiation oncologists, medical oncologists, and other healthcare professionals involved in the treatment of prostate cancer. The topics focus on current technical aspects of diagnosis and treatment of localized and advanced disease, particularly regarding imaging, technology, and training in the related devices. Dr. Zelefsky presented this lecture during the 24th SPCS in 2019. In 2020, the 25th SPCS will also offer training sessions involving imaging, scanning, and prostate cancer treatment related devices on site. Please visit this page in order to register for future SPCS meetings.