ESTRO 2025 - Abstract Book

S2269

Interdisciplinary – Health economics & health services research

ESTRO 2025

networks to all radiation oncologists and medical physicists in Tunisia.The questions addressed both the overall practice of SIB, its specific indications and underlying physical rationale.

Results: Forty-seven responses were received out of 116 (40% response rate) from 12 radiotherapy departments Tunisia. Of the respondents, 55% used SIB routinely, 13% occasionally, and 32% not at all. SIB was most commonly applied to head and neck cancers (66%), gynecological cancers (59%), prostate cancers (27.7%), and breast cancer (6%). The main reasons for using SIB were to reduce treatment time (65%), increase dose per fraction (61%), improve target volume coverage (46%), and facilitate dosimetric planning (34%). The prescribed minimum dose per fraction for all cancer sites in a SIB approach was 1.6 Gy, 1.7 Gy, and 1.5 Gy in 66%, 21%, and 14% of cases, respectively. The maximum doses per fraction (DMPPF) for H&N cancers were 2 Gy, 2.12 Gy, and 2.2 Gy in 45%, 27%, and 12% of cases, respectively. For prostate cancers, DMPPF were 2 Gy and 2.12 Gy in 34% and 14% of cases, respectively. For gynecological cancers, DMPPF were 2 Gy, 2.2 Gy, and 2.25 Gy in 23%, 42%, and 29% of cases, respectively. For breast cancers, DMPPF were 2.7 Gy and 3.2 Gy in 14% and 31% of cases, respectively. Ninety-nine percent of participants expressed intent to adopt SIB, with 11% not planning to implement it. Proposed uses included prostate cancers with lymph node boost (65%), gynecological cancers with lymph node or parametrial boost (56%), breast cancers (53%), and H&N cancers (16%). Barriers to adoption included lack of training (65%), insufficient scheduling pressure (33%), and lack of dosimetric interest (13%). Conclusion: SIB protocols are well-established for H&N and gynecological cancers, thanks to the RTOG 9003 and EMBRACE II trials, but remain underused in Tunisia due to a lack of specific training. A continuous training program, supported by national societies (STOR), could enhance SIB adoption and practice. Digital Poster Global Quantitative Analysis of Clinical Trials in Radiation Oncology Benoit Allignet 1,2 , Waisse Waissi 1 , Floriane Izarn 3 1 Radiation Oncology, Centre Léon Bérard, Lyon, France. 2 CREATIS, Université Claude Bernard Lyon 1, Villeurbanne, France. 3 Medical Oncology, Centre Léon Bérard, Lyon, France Purpose/Objective: Oncology treatments have considerably evolved thanks to clinical trials. Nevertheless, significant disparities persist, particularly in radiotherapy practice 1 . This study aimed to evaluate geographical inequalities in access to clinical trials worldwide, focusing on brachytherapy and radiotherapy. Material/Methods: ClinicalTrial.gov database was searched on June 13th, 2024, for all trials related to oncology since 2000. We identified records related to brachytherapy, external beam radiotherapy (EBRT, without brachytherapy) and other oncological trials. International repartition was analyzed at various scales: countries, continent and income groups according to World Bank's classification. To better consider the multicenter design, the number of trial sites was calculated by multiplying the number of trials by the number of sites. Keywords: National survey, Simultaneous integrated boost 803