ESTRO 2020 Abstract book

S23 ESTRO 2020

therapy (IMRT) for the treatment of men with high-risk prostate cancer. We aimed to compare patient-reported outcomes of IMRT to the prostate and the pelvic lymph nodes (PPLN-IMRT) compared to prostate only IMRT (PO- IMRT). Material and Methods Patients diagnosed with high-risk or locally advanced prostate cancer in the English National Health Service, between April 2014 and September 2016, and treated with IMRT were identified from the National Prostate Cancer Audit. Men were mailed a questionnaire 18 months after diagnosis. Patient-reported sexual, urinary, bowel and hormonal function domains using the EPIC-26, and generic health-related quality of life (HRQoL) using EQ-5D-5L, were collected from patient surveys. Comparator groups (PPLN-IMRT versus PO-IMRT) were compared using linear regression, adjusting for baseline patient, tumour and treatment characteristics. Results Of the 5468 men (78%) who responded to the patient survey, 4196 (77%) received PO-IMRT and 1272 (23%) received PPLN-IMRT. Adjusted mean scores for urinary, bowel, and hormonal EPIC-26 domains, and HRQoL were similar irrespective of the treatment region. Patients receiving PPLN-IMRT reported worse sexual function than those receiving PO-IMRT (-2.26 adjusted mean difference on a 0-100 scale; 95% CI: -3.66 to -0.86, P =0.002) but this was not a clinically meaningful difference. Conclusion PPLN-IMRT is not associated with clinically important differences in patient-reported toxicity for men with high- risk or locally advanced prostate cancer. Results from ongoing trials will provide further insight into the anti- cancer effectiveness of PLN irradiation. PD-0058 Duration of Androgen Deprivation Therapy based on Nadir PSA in High Risk Localized Prostate Cancer Z. Ayoub 1 , J. Khader 2 , M. Bulbul 3 , R. Khauli 3 , T. Andraos 1 , A. Shamseddine 4 , D. Mukherji 4 , F. Geara 1 1 American University of Beirut Medical Center, Radiation Oncology, Beirut, Lebanon ; 2 King Hussein Cancer Center, Radiation Oncology, Amman, Jordan ; 3 American University of Beirut Medical Center, Division of Urology, Beirut, Lebanon ; 4 American University of Beirut Medical Center, Division of Medical Oncology, Beirut, Lebanon Purpose or Objective We have previously shown that a nadir PSA (nPSA) of 0.06 ng/mL is a strong independent predictor of biochemical recurrence-free survival (bRFS) in patients with intermediate or high risk (HR) prostate cancer treated with definitive external beam radiation therapy (RT) and androgen deprivation therapy (ADT). We aimed to examine the association between the duration of ADT and bRFS in HR localized prostate cancer patients, based on nPSA. Material and Methods Between 1995 and 2015, 375 patients with intermediate and HR localized prostate cancer who received definitive RT and ADT were identified. A total of 235 patients had HR prostate cancer, of whom 204 patients had available data on their posttreatment nPSA and consisted our study cohort. Duration of ADT varied among patients depending on physician preference, patient tolerance, and/or compliance. A total of 157 patients (77.0%) reached the desired nPSA of less than 0.06 ng/mL, while 47 patients (23.0%) had a nadir PSA equal or more than 0.06 ng/ml. Survival outcomes were calculated using Kaplan-Meier methods and compared using the log-rank test. Predictor of outcomes were analyzed using logistic regression. P- value less than 0.05 was considered statistically significant. Results The median age for the entire cohort of 204 patients was 70 years. In patients who reached a nPSA of less than 0.06

impact on RT-induced toxicity of these comorbidities. Based on this background, we evaluated in a retrospective observational study the mixed effect of comorbidities and RT delivery on both acute and late GI and GU toxicity in PC. Material and Methods We included 1617 PC patients of which 1027 underwent definitive RT (dRT) and 590 adjuvant RT (aRT). RTOG- EORTC scales were used for toxicity assessment. Parameters evaluated were age, BMI, comorbidities, Charlson Comorbidity Index (CCI), lifestyles and parameters related to the delivery of RT. A univariate and multivariable analysis was assessed with Chi-square test and logistic regression model, Kaplan-Meier method and Cox regression model, for acute and late toxicity, respectively. Results A correlation between greater minimum margin CTV-PTV and lower acute GI toxicity was observed at multivariable model (p< 0.001) for dRT patients. Furthermore, multivariable analysis confirmed that age ≥ 66 years is associated to a higher rate of late GI toxicity both in the whole cohort of patients (HR: 2.70, 95% CI 1.15-6.39, p= 0.022) and in the aRT cohort (HR: 7.98, 95% CI 1.36-46.66, p= 0.021). A higher dose per fraction (> 2.0 Gy) was associated to GI late toxicity< G2 in patients undergoing aRT (HR: 7.13, 95% CI 1.93-23.24, p= 0.003). A higher incidence of late GI toxicity was also observed in patients undergoing aRT, in case of greater CCI score incorrect for age (HR: 0.13, 95% CI 0.02-0.77, p= 0.025). The same relation was observed for patients undergoing dRT, with the diabetes-hypertension-COPD score (HR: 1.67, 95% CI 1.04-2.69, p= 0.033). Furthermore, for dRT patients late GI toxicity was lower using cone-beam CT (HR: 0.10, 95% CI 0.01-0.81, p= 0.031). and was greater in case of acute toxicity ≥ 2 (p= 0.015). GU toxicity was reduced for dRT patients if treated with image guided RT (fiducial markers: HR: 0.03, 95% CI 0.00-0.25, p= 0.001, or cone beam CT: HR: 0.02, 95% CI 0.00-0.23,vp= 0.001) or with RT advanced modulated techniques (HR: 0.33, 95% CI 0.0-0.25, p= 0.018), as well as in case of greater CTV-PTV margin (HR: 0.10, 95% CI 0.02-0.44, p= 0.002). In the overall population a late GU toxicity < 2 was observed in case of delivery of ≥ 72.8 Gy to prostate or prostate bed, while an acute GU toxicity >2 was predictive of late GU toxicity ≥ 2 (HR 2.99, 95%CI 1.22-7.29, p=0.016). Conclusion Our analysis demonstrate that age and comorbidity have a significant impact on RT toxicity for PC, as well as the use of image-guided RT and advanced technique of delivery. On the contrary, significant correlations with lifestyles have not emerged, according to multivariate analysis. PD-0057 Patient-reported outcomes after prostate only vs prostate and pelvic lymph node radiation therapy. M. Parry 1 , J. Nossiter 2 , T. Cowling 1 , A. Sujenthiran 2 , B. Berry 1 , P. Cathcart 3 , N. Clarke 4 , H. Payne 5 , J. Van der Meulen 1 , 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, Salford, 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 Little is known about the toxicity of pelvic lymph node (PLN) irradiation following intensity-modulated radiation