A rectal spacer with hyaluronic acid can reduce the risk of gastrointestinal toxicity from hypofractionated radiation therapy in patients with prostate cancer, according to research published in JAMA Oncology.

The researchers noted that hypofractionated radiation therapy for prostate cancer is more convenient and cost effective than conventionally fractionated radiation therapy, but it has been associated with greater acute grade 2 gastrointestinal toxic effects. Rectal spacers create distance between the prostate and rectum, thereby reducing the rectal volume receiving a high radiation dose.

Researchers conducted a clinical trial evaluating rectal spacers in 201 patients treated at 12 centers in the United States, Australia, and Spain. Patients were randomly assigned to receive a hyaluronic acid spacer plus fiducial markers (136 patients) or fiducial markers only (65 patients) followed by hypofractionated radiation therapy.

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The primary outcome was a 25% or greater reduction in the rectal volume receiving 54 Gy (V54) of radiation. The investigators hypothesized that more than 70% of patients in the spacer group would achieve this primary outcome. The trial had a 6-month follow-up period.

Results showed that 98.5% of patients in the spacer group met the primary outcome. The mean reduction in rectum V54 was 85%. In addition, 2.9% of the spacer recipients experienced grade 2 or higher gastrointestinal toxic effects, compared with 13.8% of the control group, a significant 10.9% difference.

“The trial results suggest that hyaluronic acid rectal spacer should be considered for patients who are receiving hypofractionated radiation therapy,” the researchers concluded.

The study population included men with biopsy-proven T1 to T2 prostate cancer with a Gleason score of 7 or less and PSA level of 20 ng/mL or less. The median age of patients in the spacer and control groups was 68.6 years and 68.4 years, respectively. The majority of patients (76.1%) were White.


Mariados NF, Orio PF III, Schiffman Z, et al. Hyaluronic acid spacer for hypofractionated prostate radiation therapy. A randomized clinical trial. JAMA Oncol. Published online February 9, 2023. doi:10.1001/jamaoncol.2022.7592

This article originally appeared on Renal and Urology News