ESTRO 2025 - Abstract Book

S782

Clinical - Gynaecology

ESTRO 2025

Thirteen radiation oncologists participated. The results show exceptional variability in the delineation of CTV. Total CTV volume was (423.1±94.9 cm 3 ) and center of mass position relative to center of mass of the union of all contours was (0.8±0.4 cm 3 ). Only 109.9 cm 3 was delineated by all researchers. The volume delineated by at least one of the researchers was 835.9 cm 3 (Figure 1). A panel of three independent radiation oncologists, who were not investigators, confirmed that there was no deviation from the national protocol (Figure 2). Conclusion: In Serbia there is a significant variation in the delineation of the CTV in patients with endometrial cancer, which is not related to belonging to a certain center, but to individual researchers. The the results pointed to the necessity to organize national workshops with the participation of all radiation oncologists who deal with gynecological oncology in order to reduce the variability in CTV delineation and radiotherapy standardization. References: 1)Van den Heerik ASVM, et al. Adjuvant therapy for endometrial cancer in the era of molecular classification: radiotherapy, chemoradiation and novel targets for therapy. Int J Gynecol Cancer. 2021;31(4):594-604. 2)Small W Jr, et al. NRG Oncology/RTOG Consensus Guidelines for Delineation of Clinical Target Volume for Intensity Modulated Pelvic Radiation Therapy in Postoperative Treatment of Endometrial and Cervical Cancer: An Update. Int J Radiat Oncol Biol Phys. 2021;109(2):413-4. 3)Plešinac Karapandžić V, et al. National protocols for the treatment of malignant tumors. Ministry of Health of the Republic of Serbia, Working Group for the Development of National Radiotherapy Protocols, Belgrade, 2022. Keywords: endometrial cancer, clinical target volume