Hyaluronic Acid Spacer for Hypofractionated Prostate Radiation Therapy: A Randomized Clinical Trial

Area of Science:

• Radiation Oncology
• Medical Physics
• Gastroenterology

Background:

• Hypofractionated radiation therapy (RT) for prostate cancer is linked to increased acute grade 2 gastrointestinal (GI) toxic effects.
• Minimizing rectal toxicity is crucial for improving patient outcomes in prostate cancer RT.

Purpose of the Study:

• To assess the efficacy of a hyaluronic acid rectal spacer in improving rectal dosimetry.
• To determine the impact of the spacer on acute grade 2 or higher GI toxic effects during hypofractionated RT.

Main Methods:

• A randomized clinical trial involving 201 patients with early-stage prostate cancer across 12 international centers.
• Patients were randomized (2:1) to receive RT with or without a hyaluronic acid rectal spacer.
• Primary outcome: reduction in rectal volume receiving 54 Gy (V54); Secondary outcome: incidence of acute grade 2+ GI toxic effects.

Main Results:

• 98.5% of patients with the spacer achieved a ≥25% reduction in rectum V54, significantly exceeding the 70% hypothesis (P<.001).
• Acute grade 2+ GI toxic effects occurred in 2.9% of the spacer group versus 13.8% in the control group (P=.01).
• The spacer demonstrated a significant reduction in rectal dose and GI toxicity.

Conclusions:

• Hyaluronic acid rectal spacer implantation is effective in improving rectal dosimetry for hypofractionated RT.
• The use of a rectal spacer significantly reduces acute grade 2 or higher GI toxic effects.
• Rectal spacing should be considered to mitigate toxicity risks in hypofractionated prostate cancer RT.