ESTRO 2025 - Abstract Book

S797

Clinical - Gynaecology

ESTRO 2025

Purpose/Objective: The aim of this study was to compare clinical outcomes and gastrointestinal toxicity between whole- and individualized-uterine radiotherapy in patients with locally advanced cervical cancer.

Material/Methods: A retrospective analysis was conducted on 220 patients with stage IB3–IVA disease treated with definitive chemoradiotherapy between 2014 and 2021 at two tertiary centers. The clinical target volume included entire uterus (whole-uterine group) or individualized uterine volume based on gross tumor with a 15 mm margin (individualized-uterine group) ( Figure 1 ). The local recurrence rate, distant recurrence rate, overall survival, and progression-free survival were evaluated using Kaplan–Meier method. The Patient-Reported Outcome version of the Common Terminology Criteria for Adverse Events was used to assess acute gastrointestinal toxicity, and a score of ≥ 3 was defined as severe gastrointestinal toxicity.

Results: Overall, 128 (58.2%) and 92 (41.8%) patients received whole- and individualized-uterine radiotherapy with median follow-up of 63.0 (IQR: 39.4-93.2) months and 64.8 (IQR: 47.3-85.6) months, respectively. The age, FIGO stage, tumor size, uterine corpus involvement, histology, use of chemotherapy, and radiation field were not significantly different between groups. The mean cervical tumor volume and PTV50 were similar between whole- and individualized uterine radiotherapy groups (cervical tumor: 50.2 mL vs. 49.9 mL; p =0.94; PTV50: 180.6 mL vs. 179.3 mL; p =0.91), whereas PTV45 was smaller in the individualized-uterine group than whole-uterine group (1260.9 mL vs.1495.0 mL; p <0.001). Compared with whole-uterine group, individualized-uterine group had significantly lower V 45Gy in small bowel, rectum, or sigmoid colon (small bowel V 45Gy : 181.0 mL vs. 116.7 mL; p <0.001; rectum V 45Gy : 36.4 mL vs. 17.5 mL; p <0.001; sigmoid colon V 45Gy : 32.5 mL vs. 15.8 mL; p <0.001). The 5-year local recurrence rate, distant recurrence rate, overall survival, and progression-free survival in the whole- and individualized-uterine groups were 4.1% vs. 0.0% ( p =0.054), 20.2% vs. 12.0% ( p =0.12), 84.9% vs. 87.6% ( p =0.48), and 74.7% vs. 84.8% ( p =0.07), respectively ( Figure 2 ). Patients who received individualized-uterine radiotherapy reported less acute severe gastrointestinal toxicity compared with those who received whole-uterine radiotherapy (5.4% vs. 23.4%, p <0.001). The 5-year rates