ESTRO 2025 - Abstract Book

S818

Clinical - Gynaecology

ESTRO 2025

Median and IQR GTV-N was 3.3 cm³(1.9-6.3), PTV-N was 14 cm³(9-22) per node, and 38 cm³(19-69) overall per patient, respectively. The overall PTV45Gy median was 1419 cm³ (IQR 1280–1639), with risk-adapted volumes as follows: small pelvis (1110 cm³, IQR 1036–1322), large pelvis (1347 cm³, IQR 1225-1499), large pelvis+inguinal (1494 cm³, IQR 1262-2203), large pelvis+para-aortic (1671 cm³, IQR 1484–1862), and large pelvis + inguinal + para-aortic (1935 cm³, IQR 1677–2284). Median GTV regression from EBRT to BT was 88%, with larger tumours and a tendency for percentual less response in T3b and T4 (details shown in figure1).

Conclusion: This study provides detailed characterization of EBRT tumour and lymph node target volumes, thereby providing qualitative and quantitative indicators for appropriate EBRT planning for LACC. The analysis also demonstrates varying significant GTV regression between T-stages post-EBRT and chemotherapy, enabling adaptive BT planning with more complex implants in larger tumours, and potentially serving as prognostic factor.

Keywords: EMBRACE II, cervical cancer, target volumes

References: 1. Pötter R, Tanderup K, Kirisits C, et al.; The EMBRACE II study: The outcome and prospect of two decades of evolution within the GEC-ESTRO GYN working group and the EMBRACE studies. Clin Transl Radiat Oncol. 2018 Jan 11:9:48-60. doi: 10.1016/j.ctro.2018.01.001 2. https://www.embracestudy.dk/UserUpload/PublicDocuments/EMBRACE%20II%20Protocol.pdf