ESTRO 2024 - Abstract Book

S239

Brachytherapy - Gynaecology

ESTRO 2024

exclusive EBRT, before P-ISBT. Ten (23.8%) women had received previous EBRT +/- brachytherapy treatments (re irradiations). In the group of patient who were treated with EBRT, 6 (14.3%) received a tumour boost, a parametrial / paracolpium boost, or both. As for the P-ISBT treatment, median total dose was 24.5 Gy (14-44), median dose per fraction was 4 Gy (2.5-5.5), and median number of fractions was 6 (4-9). Median number of interstitial needles was 16 in MUPIT patients, and 14 in MRI-based applicator patients. Mean CTV volume was 104.5cc in MUPIT, and 62.6cc in MRI-based applicator (p=0.01). Mean D90-CTV was 62.2Gy in MUPIT, and 71.3Gy in MRI-based applicator (p=0.04). Mean Rectal D2cc was 66.4Gy in MUPIT, and 65.3Gy in MRI-based applicator. Median Bladder D2cc was 72Gy in MUPIT, and 68.9Gy in MRI-based applicator. Grade 1-2 toxicities were cystitis 4.8% (n=2) in 1 patient treated with MUPIT (grade 2), and 1 patient treated with MRI-based applicator (grade 1); Vesicovaginal fistula 2.4% (n=1, Grade 2, in one patient treated with MUPIT), rectal hemorrhageis 23.8% (n=10. 8 treated with MUPIT, and 2 treated with MRI-based applicator, both patients grade 1; p=0.01). All of the patients who needed Argon gas treatments for rectal hemorrhage had received P-ISBT with MUPIT. Grade 3 toxicity was 9.5% (n=4) vaginal stenosis, 3 patients (7.2%) with rectovaginal fistula (2 of them treated with MUPIT, and 1 treated with MRI-based applicator), and 1 patient 2.4% treated with MUPIT, who developed a vesico-recto-vaginal fistula.