The European Society for Radiotherapy & Oncology (ESTRO) Advisory Committee for Radiation Oncology Practice (ACROP) panel on prostate bed delineation reflected on macroscopic local recurrences in patients referred for postoperative radiotherapy (PORT), a challenging situation without standardized approach, and decided to propose a consensus recommendation on target volume selection and definition.
An ESTRO ACROP contouring consensus panel consisting of 12 radiation oncologists and one radiologist, all with subspecialty expertise in prostate cancer, was established. Participants were asked to delineate the prostate bed clinical target volumes (CTVs) in two separate clinically relevant scenarios: a local recurrence at the seminal vesicle bed and one apically at the level of the anastomosis. Both recurrences were prostate-specific membrane antigen (PSMA)-avid and had an anatomical correlate on magnetic resonance imaging (MRI). 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.
Contouring of the two cases confirmed considerable variation among the panelists. Finally, however, a consensus recommendation could be agreed upon. Firstly, it was proposed to always delineate the entire prostate bed as clinical target volume and not the local recurrence alone. The panel judged the risk of further microscopic disease outside of the visible recurrence too high to safely exclude the rest of the prostate bed from the CTV. A focused, "stereotactic" approach should be reserved for re-irradiation after previous PORT. Secondly, the option of a focal boost on the recurrence was discussed.
Radiation oncologists are increasingly confronted with macroscopic local recurrences visible on imaging in patients referred for postoperative radiotherapy. It was recommended to always delineate and irradiate the entire prostate bed, and not the local recurrence alone, whatever the exact location of that recurrence. Secondly, specific dose-escalation on the macroscopic recurrence should only be considered if an anatomic correlate is visible. Such a focal boost is probably feasible, provided that OAR constraints are prioritized. Possible dose is also dependent on the location of the recurrence. Its potential benefit should urgently be investigated in prospective clinical trials.
Clinical and translational radiation oncology. 2023 Sep 23*** epublish ***
Piet Dirix, Alan Dal Pra, Vincent Khoo, Christian Carrie, Cesare Cozzarini, Valérie Fonteyne, Pirus Ghadjar, Alfonso Gomez-Iturriaga, Nina-Sophie Schmidt-Hegemann, Valeria Panebianco, Almudena Zapatero, Alberto Bossi, Thomas Wiegel
Department of Radiation Oncology, Iridium Network, Antwerp, Belgium., Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, USA., Department of Clinical Oncology, The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, London, UK., Radiotherapy Department, Leon Bérard Center, Lyon, France., Department of Radiotherapy, IRCCS San Raffaele Scientific Institute, Milan, Italy., Department of Radiotherapy-Oncology, Ghent University Hospital, Ghent, Belgium., Department of Radiation Oncology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Germany., Radiation Oncology, Biocruces Bizkaia Health Research Institute, Cruces University Hospital, Barakaldo, Spain., Department of Radiation Oncology, University Hospital, LMU Munich, Germany., Department of Radiological Sciences, Oncology and Pathology, Sapienza University of Rome, Rome, Italy., Department of Radiation Oncology, La Princesa University Hospital, Health Reasearch Institute Princesa, Madrid, Spain., Radiation Oncology, Centre Charlebourg, La Garenne Colombe, France., Department of Radiation Oncology, University Hospital Ulm, Ulm, Germany.