ESTRO 2021 Abstract Book

S599

ESTRO 2021

of PRUI worsening is shown in Table 1, including the performance of the resulting models in terms of area under curve (AUC) and goodness of fit (Hosmer-Lemeshow test).

Conclusion Baseline urinary incontinence status and radiotherapy intent are the major factors predicting 2-year patient- reported urinary incontinence. The impact of RT intent (ADV/SALV vs RAD) is stronger for the “objective” (frequency and amount) PRUI symptoms. Both psychoticism and lie personality trait (a measure of social acquiescence) significantly reduce patient perception of the detrimental effect of PRUI on their QoL. PD-0768 Treatment-related toxicity of prostate bed versus whole pelvis post-prostatectomy radiation therapy M. Parry 1 , A. Sujenthiran 1 , J. Nossiter 2 , M. Morris 2 , B. Berry 1 , P. Cathcart 3 , N. Clarke 4 , H. Payne 5 , J. van der Meulen 1 , A. Aggarwal 1 1 London School of Hygiene and Tropical Medicine, Health Services Research and Policy, London, United Kingdom; 2 The Royal College of Surgeons of England, Clinical Effectiveness Unit, London, United Kingdom; 3 Guy’s and St Thomas’ NHS Foundation Trust, Urology, London, United Kingdom; 4 The Christie and Salford Royal NHS Foundation Trusts, Urology, Manchester, United Kingdom; 5 University College London Hospitals, Oncology, London, United Kingdom Purpose or Objective There is debate about the effectiveness and toxicity of pelvic lymph node (PLN) irradiation when used for disease recurrence following radical prostatectomy. This study compared the toxicity of radiation therapy (RT) to the prostate bed and pelvic lymph nodes (PBPLN-RT) with prostate-bed only radiation therapy (PBO-RT). Materials and Methods Patients with prostate cancer who underwent post-prostatectomy RT in the English National Health Service between 2010-2016 were identified by using data from the Cancer Registry, the National Radiotherapy Dataset, and Hospital Episode Statistics, an administrative database of all hospital admissions. Follow-up was available up to December 31, 2018. Validated indicators were used to identify patients with ≥ Grade 2 gastrointestinal (GI) and genitourinary (GU) toxicity according to the presence of both a procedure code and diagnostic code in patient Hospital Episode Statistics records. A competing risks regression analysis, with adjustment for patient and tumour characteristics, estimated subdistribution hazard ratios by comparing GI and GU toxicity for PBPLN-RT vs PBO-RT. Results 5-year cumulative incidences in the PBO-RT (n= 5,087) and PBPLN-RT (n= 593) groups was 18.2% and 15.9% for GI toxicity, respectively. For GU toxicity it was and 19.1% and 20.7%, respectively. There was no difference in GI or GU toxicity between PBO-RT and PBPLN-RT (GI: adjusted sHR, 0.90, 95% CI, 0.67 to 1.19; P= 0.45); (GU: adjusted sHR, 1.18, 95% CI, 0.98 to 1.44; P= 0.09). Conclusion Including PLNs in the radiation field following radical prostatectomy is not associated with a significant increase in rates of ≥ Grade 2 GI or GU toxicity at 5 years. PD-0769 Patient-reported acute intestinal toxicity and impact on patient QoL after WPRT for prostate cancer B. Noris Chiorda 1 , F. Munoz 2 , G. Sanguineti 3 , D. Cante 4 , J.M. Waskiewicz 5 , B. Avuzzi 6 , V. Vavassori 7 , M. Gatti 8 , G. Girelli 9 , A. Magli 10 , A. Pastorino 11 , L. Ferella 2 , A. Faiella 12 , C. Piva 4 , P. Ferrari 5 , E. Villa 13 , B. Farina 9 , E. Moretti 10 , T. Rancati 14 , F. Badenchini 14 , A. Bresolin 15 , R. Valdagni 16 , N. Di Muzio 17 , C. Fiorino 18 , C. Cozzarini 19 1 Fondazione IRCCS Istituto Nazionale dei Tumori, Radiotherapy, Radiotherapy, Milan, Italy; 2 Ospedale