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

Alan Dal Pra; Piet Dirix; Vincent Khoo; Christian Carrie; Cesare Cozzarini; Valérie Fonteyne; Pirus Ghadjar; Alfonso Gomez-Iturriaga; Valeria Panebianco; Almudena Zapatero; Alberto Bossi; Thomas Wiegel

doi:10.1016/j.ctro.2023.100638

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

Clin Transl Radiat Oncol. 2023 May 9:41:100638. doi: 10.1016/j.ctro.2023.100638. eCollection 2023 Jul.

Authors

Affiliations

¹ Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, USA.
² University of Bern, Bern University Hospital, Bern, Switzerland.
³ Department of Radiation Oncology, Iridium Network, Antwerp, Belgium.
⁴ Department of Clinical Oncology, The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, London, UK.
⁵ Radiotherapy Department, Leon Bérard Center, Lyon, France.
⁶ Department of Radiotherapy, IRCCS San Raffaele Scientific Institute, Milan, Italy.
⁷ Department of Radiotherapy-Oncology, Ghent University Hospital, Ghent, Belgium.
⁸ Department of Radiation Oncology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Germany.
⁹ Radiation Oncology, Biocruces Health Research Institute, Cruces University Hospital, Barakaldo, Spain.
¹⁰ Department of Radiological Sciences, Oncology and Pathology, Sapienza University of Rome, Rome, Italy.
¹¹ Department of Radiation Oncology, Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria IP, Madrid, Spain.
¹² Radiation Oncology, Centre Charlebourg, La Garenne Colombe, France.
¹³ Department of Radiation Oncology, University Hospital Ulm, Ulm, Germany.

Abstract

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 margin, extracapsular extension, and seminal vesicles 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 mails 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 videoconferences 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.There is important variability in existing contouring guidelines for postoperative prostate bed (PB) radiotherapy (RT) after radical prostatectomy. This work aimed at providing a contemporary consensus guideline for PB delineation. An ESTRO ACROP consensus panel including radiation oncologists and a radiologist, all with known subspecialty expertise in prostate cancer, delineated the PB CTV in 3 scenarios: adjuvant RT, salvage RT with PSA progression, and salvage RT with persistently elevated PSA. None of the cases had evidence of local recurrence. Contours were analysed qualitatively using heatmaps for visual assessment of controversial regions and quantitatively using Sorensen-Dice coefficient. Case-specific questionnaires were also discussed via e-mails and videoconferences for consensus. Several controversial areas of the PB CTV were identified based on both heatmaps and questionnaires. This formed the basis for discussions via videoconferences. Finally, a contemporary ESTRO-ACROP consensus guideline was developed to address areas of dissonance and improve consistency in PB delineation, independent of the indication.

Keywords: Adjuvant radiotherapy; Postoperative radiotherapy; Prostate cancer; Prostate cancer guidelines; Salvage radiotherapy; Target volume delineation.

Publication types

Review