ESTRO 2025 - Abstract Book

S832

Clinical - Gynaecology

ESTRO 2025

2516

Digital Poster A single-institution retrospective analysis of prophylactic extended field radiation therapy with chemotherapy in FIGO stage IB to IVA cervical cancer Karen Anne A Aguirre-Meneses, Alison Faye O Chan, Miguel Paulo B Lacanilao, Dustin Jan L Cruz, Lori Belle B Lofranco, Henri Cartier S Co, Gaudencio P Vega Radiation Oncology, Augusto P. Sarmiento Cancer Institute, The Medical City, Pasig, Philippines Purpose/Objective: Cervical cancer is the 2 nd most common cancer among women in the Philippines, with approximately 7,897 new cases diagnosed annually and 4,052 deaths attributed to the disease. The standard of care in treating locally advanced cervical cancer (LACC) without gross paraaortic involvement is pelvic external beam radiation therapy (EBRT) concurrent with chemotherapy followed by brachytherapy. Paraaortic region remains a common site of relapse after definitive treatment. However, the role of prophylactic extended field radiation therapy (EFRT) remains controversial. The primary endpoints of this study were overall survival (OS), locoregional control (LRC), progression-free survival (PFS) and distant metastasis-free survival (DMFS). Secondary endpoints included severity of acute and late side effects of treatment and prognostic factors affecting treatment outcomes. Material/Methods: A total of 439 cases of cervical cancer FIGO Stage IB (Bulky) to Stage IVA who were treated from January 2017 to April 2023 were reviewed. Only 163 cases were eligible for analysis. All patients received pelvic EBRT with or without prophylactic EFRT concurrent with chemotherapy, followed by HDR brachytherapy via conventional technique. OS, LRC, PFS and DMFS were estimated using the Kaplan-Meier curves. Variables with significant ( p <0.05) results in the univariate analysis underwent multivariate analysis via Cox regression models. A matched-pair analysis between treatment groups was performed based on stage. Severity of side effects between treatment groups was compared using Pearson’s chi-square test. Results: Prophylactic EFRT group showed better 3-year LRC (76.00% vs 66.40%, p =0.000) as compared to pelvic RT group. However, pelvic RT group demonstrated superior 3-year OS (91.10% vs 74.69%, p =0.042), 3-year PFS (66.10% vs 53.60%, p =0.000), and 3-year DMFS (79.00% vs 59.40%, p =0.000). After matched-pair analysis based on stage, the OS, LRC, PFS and DMFS were not statistically significant. Majority of patients (96.32%) received 3DCRT technique rather than IMRT. Most of them experienced CTCAE Grade 1-2 acute toxicities with higher incidence of CTCAE Grade 1 vomiting (45.28% vs. 9.64%, p =0.000) observed in the prophylactic EFRT group. Stage, local failure, distant failure and combined failures were significant predictors of overall survival after multivariate analysis. In univariate analysis, enlarged pelvic lymph nodes and pelvic side wall invasion were also found to impact OS, PFS, and DMFS, while parametrial invasion and primary tumor size were associated with disease progression.