Recent findings suggest that rectal spacers containing hyaluronic acid can reduce the risk of gastrointestinal toxicity from hypofractionated prostate cancer radiotherapy.
Hypofractionated radiotherapy for prostate cancer is more convenient and cost-effective than conventionally fractionated radiotherapy but is associated with greater grade 2 acute gastrointestinal toxic effects. The rectal spacer creates distance between the prostate and rectum, thereby reducing the volume of the rectum that receives high radiation doses.
A team led by Martin King, MD, of Brigham and Women’s Hospital in Boston, Massachusetts, conducted the clinical trial from March 2020 to June 2021, involving 12 sites in the United States, Australia, and Spain. This study had a follow-up period of 6 months. They randomized 201 patients to receive either a hyaluronic acid spacer plus a fiducial marker (136 patients) or a fiducial marker alone (control group, 65 patients) followed by hypofractionated radiotherapy. Randomly assigned.
The primary outcome was ≥25% reduction in rectal volume irradiated with 54 Gy (V54). The researchers hypothesized that more than 70% of patients in the spacer group would achieve this primary outcome.
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The results showed that 131 of 133 patients (98.5%) in the spacer group (the researchers excluded three patients from the primary efficacy analysis) experienced the primary outcome, Dr. King et al. reported. JAMA Oncology. The mean reduction in rectal V54 was 85%. Additionally, 2.9% of spacer recipients experienced grade 2 or higher gastrointestinal toxicity compared to 13.8% of the control group, a significant difference of 10.9%.
“Study results suggest that hyaluronic acid rectal spacers should be considered for patients receiving hypofractionated radiotherapy,” the researchers concluded.
The study population included men with biopsy-proven T1-T2 prostate cancer with a Gleason score of 7 or less and a PSA level of 20 ng/mL or less. The median age of patients in the spacer and control groups was 68.6 and 68.4 years, respectively. The majority of patients (76.1%) were Caucasian.
reference
Mariados NF, Orio PF III, Shiffman Z, et al. Hyaluronic acid spacer for hypofractionated prostate radiotherapy.randomized clinical trial. JAMA Oncor. Published online on February 9, 2023. doi:10.1001/jamaoncol.2022.7592