ESTRO 2025 - Abstract Book

S820

Clinical - Gynaecology

ESTRO 2025

Keywords: Molecular Signature, Cervical cancer

References: Figure 1. Lasso plot showing the association of each variable with the response to the CRT over time, with the addition of new patients to the model: coefficient > 0 radiosensitivity, coefficient < 0 radioresistance. Rt_gb=white blood count; pi= parametrial invasion; SCC= squamous cell carcinoma; BMI=body mass index; ln=lymph node metastasis; rt_hbg=hemoglobin; HPV=human papilloma virus; TV=tumor volume; rt_neu=neutrophil.

2090

Digital Poster Long-term Result of Adjuvant Small Pelvis EBRT for Early-stage Cervical Cancer with Intermediate Risk Factors

Pantea Bayatfard, Sezin Yuce Sari, Melis Gultekin, Ferah Yildiz Radiation Oncology, Hacettepe University, Ankara, Turkey

Purpose/Objective: To report the long-term results of adjuvant small pelvis irradiation (SPIR) in early-stage cervical patients with intermediate-risk (IR) factors (e.g., lymphovascular space invasion [LVSI], deep cervical stromal invasion [DSI], tumor size ≥4 cm, and adenocarcinoma histology) and compare the results to wide pelvis irradiation (WPIR). Material/Methods: Patients treated with surgery and adjuvant external beam radiotherapy (EBRT) between 2000 and 2020 were retrospectively evaluated. Patients with either only DSI or ≥2 IR factors were included in the study. Adjuvant RT was delivered as 2D conventional, 3D conformal, or intensity-modulated RT (IMRT) to 45-50.4 Gy. The clinical target volumes (CTV) included the surgical bed and presacral lymphatics for SPIR, and common, internal, and external iliac, and obturator lymphatic areas were also included for WPIR. Results: This study included 158 patients; 128 patients received SPIR and 30 received WPIR. Median follow-up for SPIR and WPIR groups were 101 and 46 months, respectively. Patients and treatment details are presented in Table 1. The 5- and 10-year local control (LC) rate was 92% and 88.5%, and pelvic control (PC) rates were both 94% in the SPIR arm. The 5-year LC and PC rate was 92% and 93% for the WPIR arm, respectively. Both rates were similar between arms (p=0.79, p=0.76), and no specific risk factors could be defined for either. The 5-year progression-free survival rate was 85% and 73% for SPIR and WPIR, respectively (p=0.24). No specific subgroup could be defined to benefit more from WPIR. Acute RT-related toxicity rate was 47% and 43% in the SPIR and WPIR arms, respectively (p=0.2), and no acute grade ≥3 toxicity developed. Late toxicity rate was slightly higher in the WPIR arm even after a shorter follow up period (17% vs. 10%, p=0.3).