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Vienna, Austria

ESTRO 2023

Session Item

Tuesday
May 16
09:15 - 10:30
Strauss 3
Guidelines
Barbara Alicja Jereczek-Fossa, Italy;
Fiona Mcdonald, United Kingdom
4070
Symposium
Interdisciplinary
10:05 - 10:15
ESTRO-ACROP guideline on prostate bed delineation for postoperative radiotherapy in prostate cancer
Alan Dal Pra, USA
SP-0998

Abstract

ESTRO-ACROP guideline on prostate bed delineation for postoperative radiotherapy in prostate cancer
Authors:

Alan Dal Pra1, Piet Dirix2, Vincent Khoo3, Christian Carrie4, Cesare Cozzarini5, Valérie Fonteyne6, Pirus Ghadjar7, Alfonso Gomez-Iturriaga8, Valeria Panebianco9, Almudena Zapatero10, Alberto Bossi11, Thomas Wiegel12

1University of Miami, Department of Radiation Oncology , Miami, USA; 2Iridium Network, Department of Radiation Oncology, Antwerp, Belgium; 3The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Department of Clinical Oncology, London, United Kingdom; 4Leon Bérard Center, Department of Radiotherapy, Lyon, France; 5IRCCS San Raffaele Scientific Institute, Department of Radiotherapy, Milan, Italy; 6Ghent University Hospital, Department of Radiation Oncology, Ghent, Belgium; 7Universitätsmedizin Berlin, Department of Radiation Oncology, Berlin, Germany; 8Biocruces Health Research Institute, Cruces University Hospital, Department of Radiation Oncology, Barakaldo, Spain; 9Sapienza University of Rome, Department of Radiological Sciences, Oncology and Pathology, Rome, Italy; 10Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria IP, Department of Radiation Oncology, Madrid, Spain; 11Centre Charlebourg, Department of Radiation Oncology, La Garenne Colombe, France; 12University Hospital Ulm, Department of Radiation Oncology, Ulm, Germany

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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.