A hyaluronic acid perirectal spacer injected prior to radiotherapy for prostate cancer associated with low long-term gastrointestinal (GI) and genitourinary (GU) toxicity. These findings were published in Radiation Oncology.

Higher radiotherapy doses delivered rectally for the treatment of prostate cancer has been associated with improved biochemical outcomes but increased risk for toxicity. Previous studies have indicated that a hyaluronic acid spacer allowed for effective delivery of lower radiotherapy doses.

In this study, long-term outcomes for 68 of the participants in the NoHarm study, a single-center phase II study conducted in Sweden between 2010 and 2016, were evaluated through 5 years. Patients had low- or intermediate-risk prostate cancer and had received transrectal hyaluronic acid injections prior to radiotherapy dose of 78 Gy in 39 fractions.

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The patients were median age 68 years, had a prostate-specific antigen level of 7.7 ng/mL, and most (56 patients) had a Gleason score of 6.

At the end of radiotherapy, 26% of patients reported grade 1 GI toxicity events, and 6% reported grade 2 GI toxicity events. At 6 months, 21%, 3%, and 2% of patients reported grade 1, 2, and 3 GI events, respectively. After 18 months, no grade 2 or higher events were reported.

The frequency of grades 2 and 3 GU events at the end of radiotherapy were 17% and 9%, respectively. At 5 years, 2% of patients reported a grade 1 or higher GU toxicity event.

Patient-reported outcomes (PRO) surveys showed that 18% and 12% of patients experienced problems with stool and 42% and 10% of patients experienced problems with urination at the end of radiotherapy and at 5 years, respectively.

This study may have been limited as the PRO questions changed during the long-term follow-up.

These data indicated that a perirectal hyaluronic acid spacer prior to radiotherapy associated with low 5-year toxicity rates.

Disclosure: Some authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Björeland U, Notstam K, Fransson P, et al. Hyaluronic acid spacer in prostate cancer radiotherapy: dosimetric effects, spacer stability and long‑term toxicity and PRO in a phase II study. Radiat Oncol. 2023;18(1):1. doi:10.1186/s13014-022-02197-x