ESTRO 2020 Abstract book

S406 ESTRO 2020

PD-0668 Longitudinal analysis of patient-reported urinary incontinence 2yr after post-prostatectomy RT E. Garibaldi 1 , A. Bresolin 2 , D. Cante 3 , G. Sanguineti 4 , F. Munoz 5 , V. Vavassori 6 , J.M. Waskiewicz 7 , G. Girelli 8 , B. Avuzzi 9 , A. Faiella 4 , E. Villa 6 , A. Magli 10 , B.N. Chiorda 9 , P. Gabriele 1 , M. Gatti 1 , T. Rancati 9 , R. Valdagni 9 , N. Di Muzio 11 , C. Fiorino 12 , C. Cozzarini 11 1 Istituto di Candiolo - Fondazione del Piemonte per l'Oncologia IRCCS, Radiotherapy, Turin, Italy ; 2 Fondazione Centro San Raffaele, Medical Physics, Milan, Italy ; 3 Ospedale di Ivrea, Radiotherapy, Ivrea, Italy ; 4 Istituto Nazionale dei Tumori “Regina Elena”, Radiotherapy, Rome, Italy ; 5 Ospedale Regionale Parini- AUSL Valle d’Aosta, Radiotherapy, Aosta, Italy ; 6 Cliniche Gavazzeni-Humanitas, Radiotherapy, Bergamo, Italy ; 7 Comprensorio Sanitario di Bolzano, Radiotherapy, Bolzano, Italy ; 8 Ospedale degli Infermi, Radiotherapy, Biella, Italy ; 9 Fondazione IRCCS Istituto Nazionale dei Tumori, Radiotherapy, Milan, Italy ; 10 Azienda Ospedaliero Universitaria S. Maria della Misericordia, Radiotherapy, Udine, Italy ; 11 Istituto Scientifico Ospedale San Raffaele, Radiotherapy, Milan, Italy ; 12 Istituto Scientifico Ospedale San Raffaele, Medical Physics, Milan, Italy Purpose or Objective To analyze the trend of urinary incontinence (UI) symptoms up to 2yr after post-prostatectomy RT (PORT). Material and Methods 219 patients (pts) underwent conventionally (n=125, 66.6- 79.8Gy) or hypo-fractionated (n=94, 65.8-76.8Gy, 2.1- 2.7Gy/fr) PORT during years 2011-2017. Their data were prospectively collected within a registered multi- institutional cohort study including the ICIQ-SF questionnaire filled in by pts at baseline (BL) and every 6 months thereafter. Here we report the results up to 2yr after PORT. Several ICIQ-based parameters were investigated: frequency and amount of urine loss (ICIQ3 and ICIQ4, respectively), the objective (OBJ=ICIQ3+4), the subjective (ICIQ5) and the total UI (ICIQ3+4+5). Based on a previous analysis, the time elapsed between surgery and RT (TTRT) <8 months identified those patients with incomplete UI recovery after surgery. Then, a longitudinal analysis of mean ICIQ scores at each time was performed by comparing: (a) pts with TTRT ≥8mo (n=110) vs those with TTRT<8mo (n=109); (b) pts who resulted “completely dry” at BL (OBJ=0, n=61) vs those experiencing objective UI symptoms (OBJ≥1, n=158) at RT start. A cohort of 74 pts, treated with radical RT and enrolled in the same study was used as reference (EQD2=74-91.4Gy for α/β=0.8Gy). Nonparametric statistical methods were used to compare ICIQ distributions both within (Wilcoxon Signed-Rank Test) and between (Mann-Whitney-Wilcoxon Test) sample groups. The completely dry rate variations were investigated along the 24mo following PORT. Analyses were performed with R software. Results The mean ICIQ score showed always a significant deterioration (p<0.05) during follow-up with respect to BL for all groups but the one with a TTRT <8mo which exhibited, however, a significantly worse UI than the group with TTRT ≥8mo (p<0.05) at all times (e.g. Fig.1 for the total UI). Pts treated with radical RT experienced only negligible UI symptoms, always much lower than PORT pts (p<0.001). Dry and non-dry pts at BL exhibited very distinct trends (p<0.001), with pts dry at BL showing the largest detriment from BL compared to no-dry pts. As reported in Fig.2, the fraction of completely dry patients at each time decreased in the first 12mo (from 29% at BL to 18% at

12mo), resulting stable between 12 and 24 months; interestingly, the fraction of dry pts after BL included also pts who were not dry at BL and who became dry over time, explaining the differences between the two curves of Fig.2 and suggesting a post-surgical recovery of UI in a small but not negligible fraction of pts despite RT.

Conclusion Pts who recover from UI before RT (DRY or TTRT>8mo) show a significant deterioration of all ICIQ scores after PORT. Since this trend is not seen in radically treated pts, PORT may play an important role. However, mean UI scores remain always significantly better in pts with TTRT≥8mo over those with TTRT<8mo, even 24mo after RT, suggesting that the magnitude of deterioration is lower than the one observed after surgery. PD-0669 Uncovering multifocality – PSMA-PET radiomic features for detection of intraprostatic microlesions A.S. Bettermann 1 , S. Spohn 1 , S. Kiefer 2 , C.A. Jilg 3 , J. Kranz-Rudolph 1 , T.F. Fassbender 4 , P. Bronsert 2 , N.H. Nicolay 1 , M. Mix 4 , J. Ruf 4 , M. Benndorf 5 , A.L. Grosu 1 , C. Zamboglou 1 1 Medical Center - University Freiburg, Radiation Oncology, Freiburg, Germany ; 2 Medical Center - University Freiburg, Surgical Pathology, Freiburg, Germany ; 3 Medical Center - University Freiburg, Urology, Freiburg, Germany ; 4 Medical Center - University Freiburg, Nuclear Medicine, Freiburg, Germany ; 5 Medical Center - University Freiburg, Radiology, Freiburg, Germany Purpose or Objective Prostate cancer (PCa) is renowned for its multifocality and especially microlesions are poorly detected in standard of