KEY POINTS
- This single-institution retrospective technical note included 20 patients with clinically localized prostate cancer treated with high-dose-rate prostate brachytherapy plus external beam radiotherapy between April 2023 and March 2024.
- 10 patients with prostate-to-anterior rectal wall distance < 5 mm received same-day hyaluronic acid rectal spacer injection immediately before brachytherapy; 10 patients with distance > 5 mm did not receive pre-brachytherapy spacer placement.
- The spacer was technically successful in 10 of 10 patients and preserved transrectal ultrasound image quality for catheter placement, contouring, and real-time treatment planning.
- Treatment used a single high-dose-rate brachytherapy fraction of 15 Gy; spacer placement improved prostate V100 from 94.5% ± 0.6% to 95.6% ± 0.5% (p < 0.001).
- Rectal V75 decreased from 0.97 ± 0.34 cc without spacer to 0.42 ± 0.25 cc with spacer (p < 0.001), with no significant differences in urethral D10 or bladder D0.1cc.
CLINICAL TAKEAWAY
Same-day hyaluronic acid rectal spacer placement may simplify transrectal ultrasound-guided high-dose-rate prostate brachytherapy workflows by preserving ultrasound visibility while reducing rectal dose. The approach is most relevant for patients with limited baseline prostate–rectal separation, where rectal constraints can threaten target coverage. But this is a small, non-randomized, single-institution dosimetric study, so it supports workflow feasibility rather than proving clinical toxicity benefit.