ESTRO 2022 - Abstract Book

S353

Abstract book

ESTRO 2022

Results The Cascade-Net framework achieved the segmentation results with a DSC of 96 ± 3%, 94 ± 1%, 92 ± 2%, 97 ± 1%, 96 ± 2% for prostate, bladder, rectum, right femur and left femur, respectively. The HD values (mm) were 0.04 ± 0.01, 0.03 ± 0.02, 0.04 ± 0.03, 0.03 ± 0.02, 0.03 ± 0.01 for prostate, bladder, rectum, right femur and left femur, respectively. There was no statistically significant difference between manual segmentation and Cascade-Net framework (P-value > 0.05).

Conclusion The results of our study demonstrate that our auto-contouring segmentation framework can be used for fast, reliable and reproducible segmentation of the prostate and OARs to facilitate the radiotherapy workflow.

PD-0410 Re-irradiation for local recurrence of prostate cancer – results of an international survey

M. Chiril ă 1 , P. Chaterjee 2 , K. Gordon 3 , G. Kacso 1,4 , B. Li 5 , W. Ma 6 , D.A. Martinez Perez 7 , J. Murgic 8 , M. Spalek 9 , S. Turner 10 , T. Zilli 11 , P. Poortmans 12 , M. Roach 3rd 13,14 1 Amethyst Radiotherapy Center, Radiation Oncology Department, Cluj-Napoca, Romania; 2 Apollo Hospitals, Department of Radiotherapy, Kolkata, India; 3 A. Tsyb Medical Radiological Research Center, Radiotherapy Department, Obninsk, Russian Federation; 4 University of Medicine and Pharmacy, Radiation Oncology Department, Cluj-Napoca, Romania; 5 University of California, Department of Radiation Oncology, San Francisco, USA; 6 Princess Margaret Hospital, Department of Surgery, Hong Kong, Hong Kong (SAR) China; 7 Oncosalud-AUNA, Radiotherapy Department, Lima, Peru; 8 Sisters of Charity Hospital, Radiation Oncology Department, Zagreb, Croatia; 9 Maria Sklodowska Curie National Research Institute, Department of Radiation Oncology, Warsaw, Poland; 10 Crown Princess Mary Cancer Centre, Radiation Oncology Department, Westmead, Australia; 11 University of Geneva, Radiation Oncology Department, Geneva, Switzerland; 12 Iridium Netwerk, Department of Radiation Oncology, Antwerp, Belgium; 13 University of California San Francisco, Department of Radiation Oncology, San Francisco, USA; 14 Helen Diller Family Comprehensive Cancer Center, Dpartment of Radiation Oncology, San Francisco, USA Purpose or Objective In case of prostate cancer local recurrence after radical radiation therapy (RT) there is no generally accepted consensus regarding indications for re-irradiation. The aim of this study was to evaluate the clinical practice and perspectives of professionals from countries where RT is being delivered. Materials and Methods A web-based survey was spread between 26 May 2020 and 16 June 2021 through social media and personal contacts to radiation, clinical and medical oncologists and to urologists involved in treating prostate cancer patients, aiming a proportional representation of countries according to the number of radiation oncology centers. The survey had a decision tree design, with a total of 45 questions. In this report we present the analysis of the data regarding Radiation (RO) and Clinical Oncologists (CO) who participated in the survey. Results We received 583 answers (91.2% RO and 8.9% CO) from 100 countries. Most work in Academic Centers (56.8%), have more than 10 years experience in treating prostate cancer (59.9%) and 47.3% have more than 10 prostate cancer patients under active treatment/month. In case of a local recurrence after RT, 493 (84.6%) reported using salvage treatments. The main reasons for not proposing salvage therapies were: life expectancy < 5 years (53.7%), rectal late toxicity ≥ G3 from previous RT (47.5%) and concomitant lymph nodal relapse (25%). For confirming local relapses, mpMRI was considered necessary by 60.1% of respondents, a biopsy with histology by 58.7%, and a PSMA-PET by 47% of them. For those not recommending any salvage treatment, the main concern regarding re-RT was its safety (77.8%) or efficacy (35.6%). If salvage therapy was considered necessary and safe, both RO’s and CO’s mentioned applying most often HDR-BT (49.3%), SBRT (45.8%), prostatectomy (41%), IMRT (29%), and LDR-BT (22.1%). From the 493 respondents who declared recommending salvage treatments, 334 (67.7%) personally treated patients with re-RT. Of those, 41.9% used EBRT only, 29.3% used BT only, and 28.7% used both EBRT and BT. When EBRT was delivered, 85.59% utilized SBRT, 58% IMRT and 7.2% proton therapy. From those usingBT,75.8% declared using HDR-BT and 32.5% LDR- BT, respectively. Concurrent use of ADT with re-RT in the setting of salvage therapy was reported by 60.2% of RO’s and CO’s. A minimum interval of 24 months between the first RT and re-RT was considered acceptable by 35.6%, while a similar proportion (32%) accepted an interval of only 12 months.