ESTRO 2025 - Abstract Book

S222

Brachytherapy - Gynaecology

ESTRO 2025

procedures completed. For each patient, only one HA spacer insertion was scheduled, either with the first or second brachytherapy fraction, limited by resource availability. Technique, operator experience, separation and safety were assessed. Results: Ten patients were included. Nine patients had cervical cancer and one patient had vaginal cancer. HA rectovaginal spacer was inserted transperineally in 2 patients and through the posterior distal vagina in 8 patients. Hydrodissection with normal saline was performed in all patients with volumes between 6.5-20 ml. HA volumes of 9-24 ml were inserted. Time taken ranged from 15-33 minutes. Radiation oncologists rated the HA easy to use. Positioning of needle and ease of injection ranged from easy to difficult. There was good visibility of the HA spacer on TRUS. On MRI assessment, there was excellent visibility of the HA spacer. Spacer volumes ranged from 13.66-32.63 cc and reduced to 8.49-30.59 cc for subsequent fractions on MRI.

HA spacer insertion was feasible in all ten patients, achieving target to rectum separation between 1.3-3.6 cm. There were no reported severe adverse complications related to spacer placement.

Conclusion: The preliminary results of this study highlight the technique, positive operator experience, feasibility, and safety of HA rectovaginal spacers in HDRBT for GYN cancers. Further patient accrual and longer follow-up will be conducted to evaluate dosimetry, toxicities, and patient-reported outcomes to contribute to the growing evidence for rectovaginal spacer use in GYN cancers.

Keywords: Rectovaginal spacer, hyaluronic acid, MRI

927

Digital Poster Evaluation of the impact of European guidelines on local control of locally advanced cervical cancer: a single-center retrospective study Benjamin Cavallier 1 , Bertille Segier 2 , Amelie Lusque 2 , Thomas Brun 3 , Alejandra Martinez 4 , Sarah Betrian 5 , Justine Attal 1 , Anne Ducassou 1 1 Radiation Oncology Department, Institut Claudius Regaud, Toulouse University Cancer Institute (IUCT) - Oncopole, Toulouse, France. 2 Biostatistics & Health Data Science Unit, Institut Claudius Regaud, Toulouse University Cancer Institute (IUCT) - Oncopole, Toulouse, France. 3 Physics Department, Institut Claudius Regaud, Toulouse University Cancer Institute (IUCT) - Oncopole, Toulouse, France. 4 Department of Surgical Oncology, Institut Claudius Regaud, Toulouse University Cancer Institute (IUCT) - Oncopole, Toulouse, France. 5 Department of Medical Oncology, Institut Claudius Regaud, Toulouse University Cancer Institute (IUCT) - Oncopole, Toulouse, France Purpose/Objective: The aim of this study was to retrospectively analyze the clinical impact of European treatment guidelines of LACC, before and after their implementation in our comprehensive cancer center. Material/Methods: We selected all patients with a non-metastatic LACC treated entirely at our center with radio-chemotherapy and image-guided adaptive brachytherapy (IGABT) from March 2015 to June 2022. Medical and dosimetric records of 156 patients were retrospectively reviewed. European guidelines were implemented in November 2018, and consisted in: modification of delineation of HR-CTV (including the grey zone), increasing dose delivery to HR-CTV for larger tumors (D90≥90Gy;EQD2 10 ) and more frequent use of interstitial needles. Patients were divided in two