ESTRO 2020 Abstract Book

S24 ESTRO 2020

Ospedale San Raffaele, Department of Medical Physics, Milan, Italy Purpose or Objective Baseline urinary incontinence (UI) is expected to strongly influence UI recovery after post prostatectomy radiotherapy (PORT), inducing clinicians, both radiation oncologists and urologists, to postpone “as much as possible” PORT, with the hope of maximizing UI recovery after prostatectomy. On the other hand, there is growing evidence that a longer time elapsed between prostatectomy and PORT (TTRT), possibly leading to higher PSA values at radiotherapy start, may be detrimental for patient’s outcome. The goal of current study was to analyze the trend of UI recovery and its predictors at PORT start. Material and Methods A population of 408 patients treated with PORT was enrolled in a registered cohort study originally aimed at developing predictive models of radiation-induced toxicities: prospectively collected baseline UI and individually assessed clinical and personality information were available, including TTRT. Self-reported UI was evaluated by means of ICIQ-SF (ICIQ); personality traits were also evaluated by means of the abbreviated 24-item version of the revised Eysenck personality questionnaire (EPQ-R). Both questionnaires were administered at PORT start. Several end-points based on baseline ICIQ-SF were investigated: frequency and amount of urine leakage (ICIQ3 and ICIQ4, respectively), “objective” UI (OBJ, ICIQ3+4), “subjective” UI (ICIQ5) and TOTAL UI (ICIQ3+4+5). The relationship between each end-point and TTRT was investigated. The association between clinical and personality variables and each end-point was tested by uni- and multivariable logistic regression analysis. Mean ICIQ scores representative of each decile in the ICIQ vs TTRT plot were fitted by a sigmoid curve. Analyses were performed with MedCalc and R software. Results TTRT was the strongest predictor of all end-points (p- values ≤0.001); all scores improved between 4 and 8 months after prostatectomy, without any additional long- term recovery (see for example Figure 1 related to TOTAL UI): the most-informative cut-offs ranged between 6.7 and 7.8 months (OR: 2.5-3.6). Neuroticism independently predicted SUBJ, TOTAL and daily frequency. Similarly, the fraction of completely dry patients (i.e.: OBJ=0) at PORT start heavily depended on TTRT (<6.9 months, OR:0.24) and older age (OR:0.94), showing a rapid increment in the first 4-8 months after surgery and then reaching a plateau value at about 10 months after prostatectomy (Figure 2).

Conclusion UI recovery after prostatectomy strongly depends on TTRT, with no further improvement starting from about 8- 9 months after surgery: this result strongly suggests that no additional benefit in terms of baseline UI recovery derives from waiting longer to deliver PORT. Higher levels of neuroticism lead to an overestimation of UI. PD-0060 Treatment-related toxicity of hypofractionated radiation therapy for prostate cancer M. Parry 1 , A. Sujenthiran 2 , J. Nossiter 2 , P. Cathcart 3 , N. Clarke 4 , H. Payne 5 , A. Aggarwal 6 1 London School of Hygiene and Tropical Medicine, Department of 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, Department of Urology, London, United Kingdom ; 4 The Christie and Salford Royal NHS Foundation Trusts, Department of Urology, London, United Kingdom ; 5 University College London Hospitals, Department of Oncology, London, United Kingdom ; 6 King’s College London, Department of Cancer Epidemiology- Population- and Global Health, London, United Kingdom Purpose or Objective Randomised controlled trials (RCTs) have demonstrated comparable early oncological outcomes after hypofractionated (H-RT) and conventionally fractionated radiation therapy (C-RT) in the radical treatment of prostate cancer (PCa). Data from these studies on the effect of hypofractionation on treatment-related (gastrointestinal) GI and (genitourinary) GU toxicity remains uncertain, and the effect of H-RT on older men with locally advanced PCa is under-reported. Material and Methods Population-based study of all patients treated with radical C-RT (n=9,106) and H-RT (n= 3,027) in all radiotherapy centres in the English National Health Service between 2014 – 2016. We identified severe GI and GU toxicity using a validated coding-framework and compared C-RT and H- RT using a competing-risks proportional hazards regression analysis. Results There was no difference in GI toxicity (C-RT: 5.0 events/100 person-years; H-RT: 5.2 events/100 person- years; adjusted sHR: 1.00, 95%CI: 0.89-1.13; p=0.95) or GU toxicity (C-RT: 2.3 events/100 person-years; H-RT: 2.3 events/100 person-years; adjusted sHR: 0.92, 95%CI: 0.77 -1.10; p=0.35) between patients who received C-RT and H- RT . Conclusion This national cohort study has demonstrated the use of H- RT in the radical treatment of PCa does not increase rates of severe GI or GU toxicity. Our findings also support the