ESTRO 2020 Abstract Book

S609 ESTRO 2020

Material and Methods Ninety-six consecutive patients were analyzed fulfilling the following inclusion criteria: histopathological confirmed adenocarcinoma of the prostate, MRI-staging of localized (T1-2) or locally advanced (T3a-b) prostate cancer (N0 M0), radiotherapy of prostate according to ESTRO guideline without pelvis. Prostate cancer risk features (low LR, intermediate IR and high HR) were stratified in accordance with D'Amico Classification. Clinical endpoints were calculated from start of radiotherapy. Results Ninety-six patients (mean age: 73 years) were treated from September 2010 to November 2017. Two low risk, 27 intermediate risk and 67 high-risk prostate cancer patients according to D’Amico risk classification were included. CovP was given in step-and-shoot - or VMAT-IMRT with 6/15 MV in 39 fractions to 78 Gy. Mean CTV-volume reached 68.5 ccm (range: 36.0-143.0 ccm). Mean initial PSA (Prostate-specific antigen)-level reached 8.9 ng/mL (range: 1.15-36.0 ng/mL). Concomitant androgen deprivation therapy (ADT) was recommended and given in 89% patients for a median time of 11 months (HR: 13 months, range: 0-40, IR: 5.4 months, range 0-24, LR: 0 months). At the time of last follow-up ADT was finished in 69% patients. After a median follow-up of 26 months (range: 3-73 months) estimated PSA-control (n=96) reached 100% (Phoenix). In one high-risk patient a local recurrence was detected by PET/CT and MRI 54 months after treatment in the ipsilateral lobe, rescue brachytherapy was performed. Prostate cancer-specific survival and the distant metastasis-free survival after 2 years reached both 100 %. Conclusion Coverage probability radiotherapy in mainly intermediate and high-risk prostate cancer patients demonstrated excellent short-term biochemical control. PO-1158 Mobile app of individualized Patient Decision Aid for prostate cancer based on predictive models. I. Halilaj 1 1 Maastricht University, Precision Mediicine, Maastricht, The Netherlands Purpose or Objective Patient Decision Aids (PDAs) supports the decision making process between multiple treatment options and increased patient involvement in Shared Decision-Making (SDM). PDAs have shown the increase of patients’ knowledge, involvement in decision-making and preventive behavior, and they lead to more appropriate use of tests and treatments. Our aim was to build a user-friendly progressive web app for a new generation of PDA called individualized PDA (iPDA) in prostate cancer. We implemented predictive models from predictcancer.org which provide individualized risks of recurrence, toxicity and death for different treatment options in the app. This app can provide the patients with specific actionable information such as treatment option side effects, advantages and disadvantages of each treatment option, and clarification of the patient’s preferences for each option. We hypothesize that this will aid the patient in making an informed treatment choice. Material and Methods The progressive web app was built in accordance with the International PDA (IPDA) Standards (ipdas.ohri.ca). In a single-center pilot study the iPDA was tested with male volunteers in the appropriate age group. All respondents filled in a System Usability Scale (SUS) questionnaire with 10 questions regarding the usability and user-friendliness of the app. SUS consists of a 10 item questionnaire with five response options for respondents; from Strongly agree to Strongly disagree. The maximum score on the SUS is 100.

stage with SMRI. Out of the 18 patients with T2b by SCT, 36% maintained this stage and 26% changed into T3a by SRMI. There were 8 patients with T2c by SCT, 37% changed into T3b. Only one patient was T4 and other was Tx with both tests.

The percentage of patients who presented changes between SCT and SMRI according to the GS (6,7,8,9,10) and the iPSA ranges (<10, 10-20, >20 ng/ml) did not differ significantly (p 0.097 and p 0.057, respectively). We did not observe differences depending on the age (≤70 years vs. >70 years) between both staging methods (p 0.46). Twenty-three patients categorized as T1-T2 by SCT changed into T3 by SMRI. The median GS in this group was higher than in the group of patients without changes (7.92 vs. 6.83; p=0.000), with no differences regarding iPSA (18.49 ng/ml vs. 16.20 ng/ml; p=0.56). Conclusion The use of mMRI promotes changes in the local staging of the majority of our patients with localized PC. Patients categorized as T1-T2 by SCT who changed into T3 by SMRI presented higher GS. PO-1157 Short-term results of coverage probability radiotherapy of MRI-staged prostate cancer J. Marzec 1 , R. Eisenmann 1 , F. Paulsen 1 , D. Wegener 1 , B. Frey 1 , C. Zamboglou 2 , A. Othman 3 , K. Nikolaou 3 , M. Alber 4 , O. Dohm 5 , D. Thorwarth 6 , D. Zips 1 , A. Müller 1 1 University Hospital Tübingen, University Department of Radiation Oncology, Tübingen, Germany ; 2 University Medical Center Freiburg, Department of Radiation Oncology, Freiburg, Germany ; 3 University Hospital Tübingen, Department of Radiology, Tübingen, Germany ; 4 Ruprecht Karls University Heidelberg, University Department of RadioOncology and Radiotherapy, Heidelberg, Germany ; 5 University Hospital Tübingen, Medical Physics- University Department of Radiation Oncology, Tübingen, Germany ; 6 University Hospital Tübingen, Section for Biomedical Physics- University Department of Radiation Oncology, Tübingen, Germany Purpose or Objective We previously studied in a phase II trial the robustness of the coverage probability concept (CovP) for prostate cancer radiotherapy. Robust treatment planning led to very low G3+-toxicity and biochemical control of 95% after 7 years. Therefore, we evaluated this concept at our University Hospital in a larger patient cohort implementing magnetic resonance imaging (MRI)-based TNM-staging.