ESTRO 2025 - Abstract Book

S223

Brachytherapy - Gynaecology

ESTRO 2025

groups: first group (69 patients) treated before the guideline’s implementation, and second group (87 patients) treated after. LC (primary endpoint) and OS rates were calculated (Kaplan-Meier method). Univariable and multivariable analyses were performed. Toxicities (CTCEAv5.0) were reported for all patients. Results: Initial characteristics were similar in both groups. Median age at diagnosis was 53 years-old (range:21-84). FIGO 2009/2018 repartition was respectively I=19.9%/3.8%, II=59.0%/21.8%, III=16.0%/69.2%, IV=5.1%/5.1%, with 84.0% of squamous cell carcinoma. All patients were treated with IMRT except one, delivering median dose of 45 Gy. Pathological nodes were treated by SIB. All patients except one received concomitant chemotherapy, 93.5% based on Cisplatin. 154 patients received MRI-based IGABT (2 had only a CT scan for dosimetry). Median OTT was 50 days (42-84). Median D90 HR-CTV was significantly higher in the second group (90.6 vs 85.3 Gy before November 2018;p<0.001;EQD2 10 ), as well as the use of IC/IS/perineal needles (71.3% vs 36.2%;p<0.001). After a median follow up of 53.3 months [95%CI:49.1;58.3], 2 and 5-year LC were respectively 84.4% [77.6;89.3] and 77.6% [69.3;84.0]. 2 and 5-year OS were 87.6% [81.2;91.9] and 73.7% [64.9;80.6]. Before November 2018, the 2-year LC was 80.7% [69.1;88.3] vs 87.3% [78.2;92.8] after and 2-year OS was 86.6% [75.9;92.8] vs 88.3% [79.4;93.5] respectively. Comparison of the two periods of treatment showed a positive but not significant impact of guideline’s implementation on LC (HR=0.72[0.36;1.47];p=0.371) and OS (HR=0.65[0.33;1.27];p=0.204). Multivariable analysis showed FIGO 2018 as a major prognosis factor for LC. Toxicity profile was the same in both groups, except for vaginal stenosis, more frequent after November 2018 (48.8% vs 32.4%;p=0.042). Conclusion: Real-life application of the European guidelines showed encouraging results in improving LC of LACC, assuming a higher D90 HR-CTV, in part thanks to the use of IC/IS needles, without increasing toxicity. References: Cibula D, Pötter R, Planchamp F , et al The European Society of Gynaecological Oncology/European Society for Radiotherapy and Oncology/European Society of Pathology Guidelines for the Management of Patients With Cervical Cancer International Journal of Gynecologic Cancer 2018; 28: 641-655. Sturdza A, Pötter R, Fokdal LU, et al. Image guided brachytherapy in locally advanced cervical cancer: Improved pelvic control and survival in RetroEMBRACE, a multicenter cohort study. Radiother Oncol . 2016;120(3):428-433. doi:10.1016/j.radonc.2016.03.011 Digital Poster An analysis of tandem-ovoid versus tandem-ring applicators: Can dosimetric differences influence applicator selection for intracavitary brachytherapy? Siddharth Vats 1 , Shivali Ranote 1 , Manish Gupta 1 , Anjali Azad 1 , Vandna Thakur 2 , Lalit Chandrakant 1 , Muninder Kumar Negi 3 , Parul Sharma 1 , Shabnum Thakur 4 , Shilpa Kaushal 5 , Mrinalini Upadhyay 1 , Jyoti Sharma 6 , Naina Negi 1 , Vineet Kumar 7 , Neeraj Parihar 1 , Nishant Sharma 8 1 Radiotherapy and Oncology, IGMC-Shimla, Shimla, India. 2 Radiotherapy and Oncology, SLBSGMCH Ner Chowk, MANDI, India. 3 Radiotherapy and Oncology, AIIMS, BILASPUR, India. 4 Radiotherapy and Oncology, DR RPGMC, Tanda, India. 5 Radiotherapy and Oncology, Dr. RKGMC, Hamirpur, India. 6 Radiotherapy and Oncology, TNMC and BYL Nair Medical College, Mumbai, India. 7 Community Medicine, IGMC-Shimla, Shimla, India. 8 Community Medicine, Dayanand Medical college, Ludhiana, India Purpose/Objective: Validation of dosimetric differences between the two most commonly utilized tandem-ovoid (TO) and tandem-ring (TR) applicators for high-dose-rate (HDR) intracavitary brachytherapy (ICB) holds the potential to assist the providers Keywords: cervical cancer , local control , IGABT 1323