3292 - What Is the Procedure-Related Complication Rate Associated with Iodinated Hydrogel Spacer Use in Prostate Radiotherapy? A Large Single-Center Experience
Presenter(s)
P. J. Kelly1, E. Bennett2, C. Buckley2, K. Molan2, M. Samuji2, and O. A. Houlihan2; 1Bon Secours Radiotherapy Cork in partnership with UPMC Hillman Cancer Centre, Cork, Ireland, 2Bon Secours Hospital Cork in partnership with UPMC Hillman Cancer Center, Cork, Ireland
Purpose/Objective(s): Hydrogel spacers are in widespread use in prostate radiation despite limited reported prospective trials. They have the potential for rectal sparing, thereby reducing toxicity and optimising patient quality of life in addition to aiding image-guidance during treatment delivery. Serious complications such as recto-urethral fistulae have been reported, however. In recent years an iodine-containing hydrogel spacer has been FDA approved. Since March 2021, an iodinated gel spacer has been offered to patients at our centre. The goal of this study was to capture real-world procedure-related complications.
Materials/Methods: A retrospective review of electronic records was performed. All patients receiving prostate hypofractionated IMRT or SBRT with iodinated spacer and fiducial insertion before CT simulation (7 days post-procedure) were included. Two trained and accredited Radiation Oncologists performed all insertions (N=613 patients, 145 cases each). All received single-dose IV antibiotic prophylaxis. SBRT followed the PACE protocol; IMRT was delivered using 60/68 Gy in 20/25 fractions, respectively.
Results: Between March 2021 and December 2025, 758 patients underwent spacer implantation. Median age was 71 (IQR 68–74). Risk groups: low (17), intermediate (490) and high-risk (245), as well as oligometastatic (6) prostate cancer. IMRT was delivered to 476 patients; SBRT to 282.
Two patients developed pelvic abscess requiring surgical drainage—one during IMRT, one within 4 weeks post-IMRT. Both completed radiotherapy without further issues. One patient developed an anterior rectal ulcer presenting with lower GI bleeding; managed conservatively, it healed over 10 months. No recto-urethral fistula occurred. Four patients developed late rectal urgency/tenesmus with urinary symptom flare at a median of 11 months post radiation; imaging showed persistent gel cavity without infection. Device/operator issues included venous intravasation or gel dispersal (18), resistance leading to abandonment (5), intraprostatic injection (2), and device jam (2).Conclusion: Iodinated spacer implantation showed a low rate of clinically relevant complications in a high-volume center when performed by clinicians experienced in transperineal prostate procedures. Prospective toxicity data relating to the iodinated gel spacer in the SABRE phase 3 trial (NCT04905069) is awaited. Patients should be advised of a procedure-related complication risk of 4-5%.
| Complication: | N (%) |
| None | 724 (96) |
| Rectal ulcer | 1 (0.1) |
| Abscess requiring incision and drainage | 2 (0.3) |
| Late rectal urgency/tenesmus associated with LUTS without abscess | 4 (0.5) |
| Venous intravasation/gel dispersal | 18 (2.4) |
| Intraprostatatic injection | 2 (0.3) |
| Resistance on injection, procedure abandoned | 5 (0.7) |
| Device jammed | 2 (0.3) |
| Total: | 34 (4.5) |