ESTRO 2025 - Abstract Book

S273

Brachytherapy - Gynaecology

ESTRO 2025

Purpose/Objective: Concurrent chemoradiotherapy followed by image-guided adaptive brachytherapy (IGABT) is the standard treatment for patients with locally advanced cervical cancer [1,2]. The purpose of this study is to describe the outcomes of the IGABT protocol from the Oncology Department of Hospital Carlos Van Buren, which is part of the Chilean public health-care system. Material/Methods: This retrospective cohort study includes patients treated with curative intent between 2019 to 2023, with locally advanced cervical cancer treated with 3DCRT or VMAT-based chemoradiotherapy, delivering 45 Gy in 25 fractions to the pelvis (from the iliac bifurcation) and up to 57.5 Gy boost to lymph nodes, without prophylactic para-aortic coverage, followed by IGABT with HDR source. Fifty percent of the patients were treated with the 3DCRT and 50% with VMAT. Clinical study was approved by the local ethics committee, data were obtained through the review of medical records and processed using STATA 18 (Statacorp LLC, USA), generating descriptive statistics and survival curves using the Kaplan-Meier method. Variable modeling was performed using Cox regression analysis. Results: 189 patients were included, with a median follow-up of 31 months. The median age was 47 years (IQR 37–59 years). Non-squamous histology accounted for 16.4% of cases. The stages distribution was Stage I, 20.6%; Stage II, 31.7%; and Stages III-IV, 42.3%. 94.1% of patients received a median of 5 cycles of cisplatin (IQR 4-5). HDR brachytherapy sessions were administered, with a median EQD2 to the high-risk CTV of 83.6 Gy (IQR 83.6 - 85.5). Overall survival at 3 years was 80%: 95% for stage I, 84% for stage II, and 71% for stages III-IVA. Overall survival was analyzed considering stage, tumor size, non-squamous histology, ECOG, age, total treatment duration, and number of weekly cisplatin cycles. Hazard ratios (95% CI): stage II 2.18 (0.57-8.28); stage III-IV 2.9 (0.8-10.5); tumor size on physical examination 1.34 (1.02-1.75); non-squamous histology 1.28 (0.4-3.5); age 0.98 (0.95-1.01); ECOG 0.8 (0.3-2.2); total treatment duration 1.04 (1.01-1.07); cisplatin cycles 0.72 (0.57-0.93). Figure 1.- Overall Survival by stage

Conclusion: The presented results confirm the excellent oncological outcomes, identifying prognostic factors for overall survival, and demonstrate that this treatment modality is feasible within the Chilean public health-care system.

Keywords: Cervical Cancer, IGABT, Overall Survival