ESTRO 2023 - Abstract Book

S837

Tuesday 16 May 2023

ESTRO 2023

1 University of Florence, Department of Experimental and Clinical Biomedical Sciences "M. Serio", Florence, Italy

Abstract Text Over the past years, the treatment landscape of breast cancer has significantly evolved. Several new anticancer agents entered clinical use or are in late clinical development. Among them many targeted therapies, including new antibody drug conjugates and immunotherapy agents, have already shown to bring improvements in clinical outcomes, and will therefore likely impact in an increasing manner on the management of breast cancer. The advent of innovative preclinical models has accelerated tumour targets’ identification and subsequent anti-cancer agents’ development, reducing the lag-time between preclinical discoveries and introduction into the clinics. This availability of new therapeutic measures raises the important question on how to integrate them with local and regional treatments, and particularly with radiation therapy, in both curative and advanced settings. The impact of new targeted agents on tumour biology, micro- and immune environment, and cellular energetics, can alter the clinical outcomes after irradiation. The purpose of this consensus is to provide preclinical and clinical evidence- and (where lacking) consensus-based guidelines on how to integrate targeted and other agents properly and safely with irradiation to improve the clinical care of patients affected by breast cancer who are candidates for these treatments. An international panel of experts in preclinical and translational research, drug development, and radiation therapy reviewed the available evidence and provide recommendations to help physicians in daily clinical practice. SP-0998 ESTRO-ACROP guideline on prostate bed delineation for postoperative radiotherapy in prostate cancer A. Dal Pra 1 , P. Dirix 2 , V. Khoo 3 , C. Carrie 4 , C. Cozzarini 5 , V. Fonteyne 6 , P. Ghadjar 7 , A. Gomez-Iturriaga 8 , V. Panebianco 9 , A. Zapatero 10 , A. Bossi 11 , T. Wiegel 12 1 University of Miami, Department of Radiation Oncology , Miami, USA; 2 Iridium Network, Department of Radiation Oncology, Antwerp, Belgium; 3 The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Department of Clinical Oncology, London, United Kingdom; 4 Leon Bérard Center, Department of Radiotherapy, Lyon, France; 5 IRCCS San Raffaele Scientific Institute, Department of Radiotherapy, Milan, Italy; 6 Ghent University Hospital, Department of Radiation Oncology, Ghent, Belgium; 7 Universitätsmedizin Berlin, Department of Radiation Oncology, Berlin, Germany; 8 Biocruces Health Research Institute, Cruces University Hospital, Department of Radiation Oncology, Barakaldo, Spain; 9 Sapienza University of Rome, Department of Radiological Sciences, Oncology and Pathology, Rome, Italy; 10 Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria IP, Department of Radiation Oncology, Madrid, Spain; 11 Centre Charlebourg, Department of Radiation Oncology, La Garenne Colombe, France; 12 University Hospital Ulm, Department of Radiation Oncology, Ulm, Germany Abstract Text Purpose/Objective: Radiotherapy to the prostate bed is a potentially curative salvage option after radical prostatectomy. Although prostate bed contouring guidelines are available in the literature, important variabilities exist. The objective of this work is to provide a contemporary consensus guideline for prostate bed delineation for postoperative radiotherapy. Methods: An ESTRO-ACROP contouring consensus panel consisting of 11 radiation oncologists and one radiologist, all with known subspecialty expertise in prostate cancer, was established. Participants were asked to delineate the prostate bed clinical target volumes (CTVs) in 3 separate clinically relevant scenarios: adjuvant radiation, salvage radiation with PSA progression, and salvage radiation with persistently elevated PSA. These cases focused on the presence of positive surgical margins, extracapsular extension, and seminal vesicle involvement. None of the cases had radiographic evidence of local recurrence on imaging. A single computed tomography (CT) dataset was shared via FALCON platform, and contours were performed using EduCaseTM software. Contours were analyzed qualitatively using heatmaps which provided a visual assessment of controversial regions, and quantitatively analyzed using Sorensen-Dice similarity coefficients. Participants also answered case-specific questionnaires addressing detailed recommendations on target delineation. Discussions via electronic mail and videoconferences for final editing and consensus were performed. Results: The mean CTV for the adjuvant case was 76 cc (SD = 26.6), salvage radiation with PSA progression was 51.80 cc (SD = 22.7), and salvage radiation with persistently elevated PSA 57.63 cc (SD = 25.2). Compared to the median, the mean Sorensen-Dice similarity coefficient for the adjuvant case was 0.60 (SD 0.10), salvage radiation with PSA progression was 0.58 (SD = 0.12), and salvage radiation with persistently elevated PSA 0.60 (SD = 0.11). A heatmap for each clinical scenario was generated. The group agreed to proceed with a uniform recommendation for all cases, independent of the radiotherapy timing. Several controversial areas of the prostate bed CTV were identified based on both heatmaps and questionnaires. This formed the basis for discussions via videoconference, where the panel achieved consensus on the prostate bed CTV to be used as a novel guideline for postoperative prostate cancer radiotherapy. Conclusion: Variability was observed in a group formed by experienced genitourinary radiation oncologists and a radiologist. A single contemporary ESTRO-ACROP consensus guideline was developed to address areas of dissonance and improve consistency in prostate bed delineation, independent of the indication.

SP-0999 ASTRO-ESTRO guideline on oligometastatic NSCLC M. Guckenberger Switzerland

Abstract not available

Symposium: Back to the future - The automated radiation oncology workflow in 2030

SP-1001 2030: The end of the "one-dose fits all" concept? J. Bibault 1 1 Hôpital Européen Georges Pompidou, Radiation Oncology, Paris, France

Abstract Text