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ORIGINAL RESEARCH article

Front. Oncol.
Sec. Radiation Oncology
Volume 15 - 2025 | doi: 10.3389/fonc.2025.1563015
This article is part of the Research Topic Radiation Therapy and Organ Preservation: Controversies and Emerging Evidence View all 9 articles

Low Incidence of Significant Hydrogel Spacer Rectal Wall Infiltration: Results from an Experienced High-Volume Center

Provisionally accepted
Sungmin Woo Sungmin Woo 1*Anton Becker Anton Becker 1Aaron E Katz Aaron E Katz 2Angela Tong Angela Tong 1Hebert A Vargas Hebert A Vargas 1David Byun David Byun 3Jonathan W. Lischalk Jonathan W. Lischalk 2Jonathan Haas Jonathan Haas 2Michael J Zelefsky Michael J Zelefsky 3
  • 1 Department of Radiology, Grossman School of Medicine, New York University, New York, New York, United States
  • 2 NYU Langone Hospital-Long Island, Mineola, New York, United States
  • 3 Department of Radiation Oncology, Grossman School of Medicine, New York University, New York City, New York, United States

The final, formatted version of the article will be published soon.

    Objectives: To evaluate the incidence and degree of rectal wall infiltration (RWI) of spacer gel used during prostate radiotherapy among two practitioners experienced in using rectal spacers.Materials and methods: Consecutive patients with prostate cancer who received prostate radiotherapy after hydrogel rectal spacer insertion in August 2023–August 2024 by two experienced practitioners were retrospectively included. Post-implant magnetic resonance imaging examinations were evaluated by two radiologists for RWI: 0 (no abnormality), 1 (rectal wall edema), 2 (superficial RWI), and 3 (deep RWI). Scores 2–3 were considered positive for RWI and their location and degree of RWI (radial, longitudinal, and circumferential) were also categorized. Inter-reader agreement was assessed with Cohen’s Kappa.Results: 215 men were included. Agreement was substantial between the radiologists for RWI scores (Kappa, 0.697; 95% confidence interval, 0.594-0.800). RWI scores were 0 in 80.5% (173/215), 1 in 7.9% (17/215), 2 in 10.7% (23/215), and, 3 in 0.9% (2/215) of the men. Altogether, RWI was present (scores 2–3) in 11.6% (25/215), most commonly in the mid-gland and apex with median radial, longitudinal, and circumferential involvement of 3.2 mm, 8.6 mm, and 11.5%. None of these patients demonstrated any significant rectal toxicity.Conclusion: RWI was very uncommon for experienced practitioners. The degree of RWI was focal and not associated with increased complications.

    Keywords: Hydrogel, Magnetic Resonance Imaging, Radiotherapy, Spacer, rectal wall infiltration

    Received: 18 Jan 2025; Accepted: 10 Feb 2025.

    Copyright: © 2025 Woo, Becker, Katz, Tong, Vargas, Byun, Lischalk, Haas and Zelefsky. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Sungmin Woo, Department of Radiology, Grossman School of Medicine, New York University, New York, 10016, New York, United States

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