ESTRO 2025 - Abstract Book

S1552

Clinical – Mixed sites & palliation

ESTRO 2025

PS 0 in 52.7% and PS 1 in 35.4%. PET/CT was the most commonly used imaging modality (67.9%), 35.0% of lesions were biopsy-confirmed. The most commonly treated regions were the thorax (49.6%), pelvis (35.0%), and abdomen (13.6%). The primary tumours were prostate (35.5%), lung including NSCLC or SCLC (27.3%), breast cancer (23.6%), rectal cancer (11.5%), gynaecological cancers (2.1%). Reirradiation was completed as planned in 96.4% of cases. 80.7% received type 1 and 16.4% type 2 re-irradiation, with 2.9% of data missing. The median prescription dose was 61.9 Gy EQD2, given in a median of 5 fractions (IQR 5 – 15, range 1 – 38). Photon therapy was the main reirradiation modality (93.6%), followed by particle therapy (2.5%) and brachytherapy (1.8%). Surgery preceded reirradiation in 29.2% of cases. 31% received concomitant systemic therapies (hormonal therapy (65.3%), chemotherapy (22.7%) and targeted therapy (14.7%), immunotherapy (2.2%), other (7.2%)). Conclusion: Initial analysis confirms European-wide recruitment to the ReCare cohort study is feasible. It demonstrates completeness of prospective real-world data collection for this patient group and therefore future reliable analyses are expected which will examine oncological outcomes, toxicity, and quality of life for this population. These data support the planned expansion of this initiative to include patients having reirradiation to the head and neck and CNS.

Keywords: reirradiation, patterns of care, prospective study

3291

Digital Poster Reirradiation: an ideal workflow from literature to every-day clinical practice

Federico Mastroleo 1,2 , Giulia Marvaso 1,2 , Gaia Piperno 1 , Annamaria Ferrari 1 , Roberta Lazzari 1 , Marianna Gerardi 1 , Elena Rondi 3 , Francesca Emiro 3 , Stefania Comi 1 , Floriana Pansini 3 , Maria Giulia Vincini 1 , Federica Cattani 3 , Roberto Orecchia 4 , Daniela Alterio 1 , Barbara Alicja Jereczek-Fossa 1,2 1 Division of Radiation Oncology, IEO European Institute of Oncology IRCCS, Milan, Italy. 2 Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy. 3 Unit of Medical Physics, IEO European Institute of Oncology IRCCS, Milan, Italy. 4 Scientific Directorate, IEO European Institute of Oncology IRCCS, Milan, Italy Purpose/Objective: Reirradiation (reRT) is a pivotal tool in the field of radiation oncology. This study aims to introduce an innovative and comprehensive framework designed for the application in curative-intent retreatments. Material/Methods: An extensive and critical review of the current literature, focusing on proposed workflows, recommendations, and dose constraints has been performed by a dedicated working group of our Division (4 MDs, 4 physicists, 1 Biomedical Engineer). This framework accommodates both scenarios: retreating the same target area (R1-type reRT) and addressing adjacent targets where there might exist a cumulative toxicity risk due to previous treatments (R2-type reRT). Results: the literature analysis has allowed us to 1) draw an internal document collecting pillars of reRT (classification, radiobiological consideration, etc); 2) collect α/β values for various tumors and dose constraints for different OAR; 3) propose a workflow that addresses the critical considerations necessary in the evaluation and decision making process for potential reRT, making it a valuable tool in everyday clinical practice in radiation oncology (Fig. 1)