ESTRO 2025 - Abstract Book

S784

Clinical - Gynaecology

ESTRO 2025

503

Digital Poster Association of long-term treatment outcomes with changes in PET/MRI characteristics in locally advanced cervical cancer patients. Radovan Vojtíšek 1 , Jan Baxa 2 , Petr Hošek 3 , Emília Sukovská 1 , Petra Kovářová 1 , Jindřich Fínek 1 1 Department of Oncology and Radiotherapyncology, University Hospital, Pilsen, Czech Republic. 2 Department of Imaging Methods, University Hospital, Pilsen, Czech Republic. 3 Biomedical Center, Faculty of Medicine, Pilsen, Czech Republic Purpose/Objective: We aimed to find predictive tumour characteristics detected by interim PET/MRI in cervical cancer patients. We also investigated the type of interim response. We also compared investigated parameters with survival outcomes (DFS, OS). Material/Methods: We evaluated 108 patients treated between August 2015 and January 2023 who were treated with IGABT and underwent staging, midtreatment evaluation, and restaging using PET/MRI. Patients were divided into two groups based on RECIST and PERCIST criteria: responders (CMR) and non-responders (non-CMR). These two groups were compared using selected parameters obtained at pre-PET/MRI, mid-PET/MRI. Early response to treatment evaluated by mid-PET/MRI was categorized into three types: Interim Complete Metabolic Response, Interim Nodal Response and Interim Nodal Persistence. Results: Mid-TLG-S parameter showed the best discriminatory ability for predicting non-CMR (AUC ROC 0.750). The second factor with significant discriminatory ability was mid-MTV-S (AUC ROC 0.726). The strongest factor, mid-TLG-S, showed a sensitivity of 40% and specificity of 90% at a threshold value of 70. We found a statistically significant association of DFS and OS with the following parameters: number of chemotherapy cycles, early response type, CMR vs. non-CMR. Conclusion: We were able to identify thresholds for selected parameters, which can be used to identify patients who are more likely to have worse DFS and OS. The type of early response during CCRT is also significantly associated with DFS and OS. These aspects are an important contribution to the possible stratification of patients for subsequent individualised adjuvant treatment.

Keywords: cervical cancer; PET/MRI; early treatment response

541

Proffered Paper STEREOTACTIC ABLATIVE RADIOTHERAPY FOR OLIGOMETASTATIC OVARIAN CANCER PARENCHYMAL DISEASE: THE MITO-RT3/RAD PHASE II TRIAL Macchia Gabriella 1 , Donato Pezzulla 1 , Maura Campitelli 2 , Simona Lucci 2 , Andrei Fodor 3 , Donatella Russo 4 , Vittoria Balcet 5 , Paolo Bonome 1 , Lorena Draghini 6 , Giuseppe Roberto D'Agostino 7 , Maria Tamburo 8 , Lucia Giaccherini 9 , Aida Di Stefano 10 , Mara Fanelli 11 , Lella Petrella 11 , Savino Cilla 12 , Mariangela Boccardi 1 , Marica Ferro 1 , Vincenzo Picardi 1 , Alessio Giuseppe Morganti 13,14 , Maria Antonietta Gambacorta 2,15 , Anna Fagotti 16 , Sandro Pignata 17 , Gabriella Ferrandina 16 , Francesco Deodato 1,15 1 Radiation Oncology Department, Responsible Research Hospital, Campobasso, Italy. 2 UOC di Radioterapia, Dipartimento di Scienze Radiologiche, Radioterapiche ed Ematologiche, Fondazione Policlinico Universitario