ESTRO 2025 - Abstract Book

S4054

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

References: Francolini G, Porreca A, Facchini G, et al. PERSIAN trial (NCT05717660): an ongoing randomized trial testing androgen deprivation therapy, apalutamide and stereotactic body radiotherapy. An alternative "triplet" for oligometastatic hormone sensitive prostate cancer patients. Med Oncol. 2023;41(1):39. Published 2023 Dec 29. doi:10.1007/s12032-023-02268-3

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Digital Poster Implantable rectal spacers (IRS) in prostate cancer radiotherapy: a systematic review Julie Lippens 1 , Louise Willems 1 , Oleksandr Boychak 2 , Michael Pinkawa 3 , Peter F Orio 3rd 4 , Michael W T Chao 5 , Suneil Jain 6 , Daniel Y Song 7 , Michael Zelefsky 8 , Evert J Van Limbergen 9 , Ben G L Vanneste 1,9 1 Department of Human Structure and Repair; Department of Radiation Oncology, Ghent University Hospital and Ghent University, Ghent, Belgium. 2 Department of Radiation Oncology, St Luke’s Radiation Oncology Network, Dublin, Ireland. 3 Department of Radiation Oncology, Wege Klinik Bonn, Bonn, Germany. 4 Department of Radiation Oncology, Dana Farber Brigham Cancer Center, Boston, Massachusetts, USA. 5 Department of Radiation Oncology, Olivia Newton John Cancer Centre and Genesis Cancer Care, Melbourne, Australia. 6 Patrick G Johnston Centre for Cancer Research, Queens University Belfast, Belfast, United Kingdom. 7 Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA. 8 Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York, USA. 9 Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, Netherlands Purpose/Objective: With an estimated 1.41 million annual incidences, prostate cancer (PC) is the second most prevalent cancer in males worldwide 1 . For low or intermediate risk PC, treatments with equal cure rates include prostatectomy, EBRT, and brachytherapy (BT). Higher radiation doses improve disease control 2,3 , but dose escalation is limited by the potential of damaging nearby organs at risk (OAR), causing genito-urinary (GU) and gastrointestinal (GI) adverse events (AEs) 4 . As PC survival rates rise, research on preventing AEs is increasingly important, emphasizing quality of life (QOL). This systematic review summarizes efficacy and safety of implantable rectal spacers (IRS) in reducing rectal dose and GI toxicity during PC RT. Material/Methods: A comprehensive literature search was conducted in July 2024. Results included both prospective and retrospective research and were limited to the English language and research in humans. The 54 included studies, all published between 2007 and 2024, focused on IRS in RT for PC and one of the following topics: IRS implantation technique, safety, AEs, spacing distance, rectal dose reduction and GI toxicity or bowel QOL. Results: One centimeter of spacing between rectum and prostate sufficed to spare the rectum, the primary dose-limiting organ. Findings indicate a favorable safety profile, with an overall complication rate of 0,96% when using hydrogel (HG) spacers. In prospective trials comparing HG to non-spacer, acute grade 1 and 2 GI toxicity occurred in 10%-43% vs. 10%-50.6% and 0%-4.1% vs. 0%-4.5%. For late toxicity, these percentages were 2%-16.6% vs. 5.6%-41.8% and 0%- 3.3% vs. 0%-6%, respectively. There was no acute grade 3, two cases of late grade 3, and no grade 4-5 GI toxicity reported in the spacer arm of clinical trials. The use of a HG spacer was associated with long-term preservation of bowel QOL. Results for other IRS types are similar, but less studied, with one randomized controlled trial (RCT) each for rectal balloon implants (RBI) and hyaluronic acid (HA), and none for human collagen (HC).

Conclusion: Integrating IRS into clinical practice offers potential to enhance the therapeutic landscape for PC patients.