ESTRO 2020 Abstract book

S667 ESTRO 2020

balloon filled-up with 100cc air to minimize rectal movements. Nineteen patients (18.27%) were treated in a Versa-HD Linac and Intra-fraction motion 4D image guidance with Clarity system (Elekta). 76P (73.08%) received premedication with alpha-1 receptor antagonist and 25p (24.04%) received androgenic deprivation therapy (ADT). Biochemical failure was assessed with Phoenix definition and toxicities were scored with Common Terminology Criteria for Adverse Events (CTCAE) V.5.

Conclusion Ultra-hypofractionated SBRT is a feasible and safe treatment for prostate cancer with an excellent biochemical relapse-free survival outcomes with minimal toxicity. PO-1177 Treatment-related toxicity using prostate only vs prostate and pelvic lymph node radiation therapy. M. Parry 1 , A. Sujenthiran 2 , T. Cowling 1 , J. Nossiter 2 , 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 There is a debate about the effectiveness and toxicity of pelvic lymph node (PLN) irradiation for the treatment of men with high-risk prostate cancer. This study compared the toxicity of intensity modulated radiation therapy (IMRT) to the prostate and the pelvic lymph nodes (PPLN- IMRT) compared to prostate only IMRT (PO-IMRT). Material and Methods Patients with high-risk localised or locally advanced prostate cancer treated with IMRT in the English National Health Service between 2010 and 2013 were identified using Cancer Registry data, the National Radiotherapy Data Set, and Hospital Episode Statistics (HES), an administrative database of all hospital admissions. Follow- up was available up to December 31, 2015. Validated indicators were used to identify patients with severe toxicity according to the presence of both a procedure code and diagnostic code in patient HES records. A competing risks regression analysis, with adjustment for patient and tumour characteristics, estimated

Results With a median follow-up of 16 months (2-40) all patients are alive; no distant relapse was observed and there was just one (0.96%) biochemical-local prostate relapse confirmed by choline PET-CT at 28.63 months in favorable- intermediate risk group patient. No genitourinary (GU) toxicity > grade 3 and gastrointestinal (GI) > grade 2 were observed, analysis of medians and acute toxicity is described in image 2. Prostatic median volume was 67.53cm 3 (18.36-188.32). We observed no worsening acute GI and GU toxicity related to the prostatic median volume.