ESTRO 2025 - Abstract Book

S850

Clinical - Gynaecology

ESTRO 2025

liver seeding cases presented notable challenges due to anatomical complexity. Most treatment plans adhered to protocol standards, but deviations were often observed in organ-at-risk (OAR) constraints, particularly involving the small bowel. These findings emphasize variability in treatment planning and challenges in achieving uniformity for complex metastases. Conclusion: The SABR-ROC trial is actively recruiting and is projected to meet its enrollment target by Q3 2025. The dummy run highlighted challenges in standardizing target delineation across centers, emphasizing the need for ongoing quality assurance and protocol refinement. Adhering to treatment protocols while balancing efficacy and OAR safety remains crucial. These insights aim to refine SABR protocols for recurrent ovarian cancer, enhancing treatment outcomes and safety.

Keywords: ovarian cancer; SABR; dummy run

3201

Digital Poster Evaluation of clinical response and toxicity of hypofractionated radiotherapy regimen versus conventional regimen in locally advanced cervical cancer José Alberto Calderón-Cordova, Regina Pantoja-Lopez, Cindy Sharon Ortiz Radiotherapy, UMAE 25, Monterrey, Mexico Purpose/Objective: To compare the clinical response and toxicity associated with radical treatment with conventional dose radiotherapy versus that observed in a hypofractionated regimen in patients with locally advanced cervical cancer. Material/Methods: Experimental, prospective study, where 22 patients were randomized to the experimental group receiving a dose of 42 Gy in 14 fractions and 22 patients were randomized to a conventional regimen of 50 Gy in 25 fractions. 80% of patients received cisplatin and underwent high dose rate brachytherapy, reaching an EQD2 of 81.2 Gy in hypofractionated regimen. Local control and acute and subacute toxicities were assessed. The research and ethics committee approved the study, and all patients signed informed consent. Results: Complete response was observed in 45.45% of patients in the experimental group and in 27.27% of patients in the control group, and partial response in 54.54% of patients in the experimental group and in 72.72% of patients in the control group ( p= 0.79). Grade 1 gastrointestinal toxicity occurred in 50% of patients in both treatment groups and grade 2 in 31.81% of patients in both treatment groups ( p= 0.65). Genitourinary toxicity of grade 1 was observed in 36.36% of patients in both treatment groups, and grade 2 in 13.63% of patients in the experimental group and 22.71% of patients in the control group ( p= 0.74). Grade 3 radiodermatitis occurred in 13.63% of patients in the experimental group ( p= 0.12). One patient in the control group had grade 3 anemia ( p= 0.03). Conclusion: Treatment with hypofractionated radiotherapy with a dose of 42 Gy in 14 fractions is equivalent to conventional treatment with a dose of 50 Gy in 25 fractions, with similar clinical responses (complete and partial), with the benefit of reducing the total treatment time of external radiotherapy, decreasing the protraction time of the shortened scheme, which can be reflected in a benefit in terms of local control and better adherence to treatment. Regarding treatment-related adverse events, the multivariate analysis did not show a statistically significant difference in terms of gastrointestinal, genitourinary and mucocutaneous toxicity. Although grade 3 mucocutaneous toxicity is