Prospective, Randomized, Controlled Pivotal Trial of Biodegradable Balloon Rectal Spacer for Prostate Radiation Therapy
Abstract
PURPOSE/OBJECTIVES
Rectal spacers have been shown to reduce rectal side effects in patients receiving prostate radiation. However, concerns remain regarding precise and reproducible gel injection. We evaluated efficacy and safety of a novel rectoprostatic spacer balloon which allows potential for controlled, adaptable deployment. This study tested co-primary hypotheses: 1) Balloon spacer would result in ≥ 25% reduction of rectal V70 in > 75% of subjects, and 2) Implantation procedure-related and rectal ≥ Grade 1 adverse events within 6 months (duration ≥ 2 days, CTCAE 4.0) would be non-inferior in balloon vs control subjects.
MATERIALS/METHODS
222 subjects were enrolled at 16 centers. All patients had T1-T3 prostate cancer without MRI evidence of posterior extraprostatic invasion. Randomization was 2:1 (balloon: control) and subject-blinded. Patients underwent transperineal TRUS-guided fiducial placement +/- balloon, followed by IMRT (81 Gy in 1.8 Gy fractions or biologically equivalent hypofractionated dose). For efficacy comparisons, plans were generated by a central core lab on pre- and post-implant CT scans.
RESULTS
The primary efficacy endpoint was met, with 97.9% of balloon subjects (139/142) having rectal V70 reduction >25% (p<0.001). Mean V70 was 7.0 % pre- vs 1.1% post- implant. The primary safety endpoint was met with balloon subjects experiencing fewer ≥ Grade 1 events, 18% vs 23% (p < 0.001 for non-inferiority). On pre-defined secondary endpoint of ≥ Grade 2…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 222 participants or records.
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