ESTRO 2025 - Abstract Book

S283

Brachytherapy - Gynaecology

ESTRO 2025

The median follow-up for HYPOCx-iRex was 23-24 months and EMBRACE-II at 38 months. There were no significant differences in age across the groups (p=0.72), with a median age of 52 years for HYPO and EMBRACE-II, and 58 years for CVRT. Most patients were staged as IIB or IIIC1. The 18-month follow-up revealed higher gastrointestinal (GI≥2/GI≥3) toxicity in HYPO 23.8%/19.1% compared to CVRT 19.8%/13.5% and EMBRACE-II 0/0 without statistical significance (p=0.09/0.08), and no significant differences for genitourinary (GU ≥2) conditions. For brachytherapy data, D90 IR-CTV and D0.1cc of sigmoid were significantly higher in HYPO (P<0.001 and 0.074). Mean iRex60 was also significantly greater in the HYPO 1.9 (IQR 1.7-2) compared to CVRT 1.7 (IQR 1.6-1.9) and EMBRACE II 1.6 (1.5-1.7) (p < 0.001), and Mean ISV60 showed marked differences across groups (p=0.035). Despite the significant correlation of iRex and ISV with grade >=2 GI toxicity in univariate COX analysis, the multivariate analysis failed to show significant correlation. While rectum D0.1cc and D2cc were also failed to demostrate correlation; mean IR-CTV volume (HR 1.14, p=0.02) and Sigmoid D0.1cc (HR 1.27, p=0.045) showed the independent correlation with grade >=2 GI toxicity.