ESTRO 2020 Abstract book

S668 ESTRO 2020

subdistribution hazard ratios (sHRs) comparing gastrointestinal (GI) and genitourinary (GU) complications for PPLN-IMRT versus PO-IMRT. Results 3-year cumulative incidence in PPLN-IMRT (n=780) and PO- IMRT (n=3,065) groups were both 14% for GI toxicity, and 9% and 8% for GU toxicity, respectively. PPLN-IMRT and PO- IMRT patients had similar levels of severe GI toxicity (adjusted sHR 1.00; 95% CI 0.80-1.24; p =0.97) and GU toxicity rates (adjusted sHR 1.10; 95% CI 0.83-1.46; p =0.50). Conclusion Including pelvic lymph nodes in radiation fields for high- risk or locally advanced prostate cancer is not associated with increased GI or GU toxicity at three years. Further follow-up is required to answer questions about its impact on late GU toxicity. Results from ongoing trials will provide further insight into the anti-cancer effectiveness of PLN irradiation. PO-1178 Identifying skeletal-related events for prostate cancer in routinely collected hospital data. M. Parry 1 , T. Cowling 1 , A. Sujenthiran 2 , J. Nossiter 2 , B. Berry 1 , P. Cathcart 3 , N. Clarke 4 , H. Payne 5 , A. Aggarwal 6 , J. Van der Meulen 1 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, Clincal Effectiveness Unit, London, United Kingdom ; 3 Guy’s and St Thomas’ NHS Foundation Trust, Department of Urology, London, United Kingdom ; 4 The Christie NHS Foundation Trust, Department of Urology, Manchester, 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 Non-osteoporotic skeletal-related events (SREs) are clinically important markers of disease progression in prostate cancer. We developed and validated an approach to identify SREs in men with prostate cancer using routinely-collected data. Material and Methods Patients diagnosed with prostate cancer between January 2010 and December 2013 were identified in the National Prostate Cancer Audit, based on English cancer registry data. A coding framework was developed based on diagnostic and procedure codes in linked national administrative hospital and routinely-collected radiotherapy data to identify SREs occurring before December 2015. Two coding definitions of SREs were assessed based on whether the SRE codes were paired with a bone metastasis code ( ‘specific definition’ ) or used in isolation ( ‘sensitive definition’ ). We explored the validity of both definitions by comparing the cumulative incidence of SREs from time of diagnosis according to prostate cancer stage at diagnosis with death as a competing risk. Results We identified 40,063, 25,234 and 13,968 patients diagnosed with localised, locally advanced and metastatic disease, respectively. Using the specific definition, we found that the 5-year cumulative incidence of SREs was 0.9% in patients with localised disease, 5.4% in patients with locally advanced disease, and 38.8% in patients with metastatic disease. Using the sensitive definition, the corresponding cumulative incidence figures were 8.4%, 13.4%, and 40.7%, respectively. Conclusion The comparison of the cumulative incidence of SREs identified in routinely collected hospital data, based on a specific coding definition in patients diagnosed with different prostate cancer stage, supports their validity as a clinically important marker of cancer progression.

PO-1179 Patient-reported outcomes following a high- dose rate brachytherapy boost for prostate cancer. M. Parry 1 , J. Nossiter 2 , T. Cowling 1 , A. Sujenthiran 2 , B. Berry 1 , P. Cathcart 3 , N. Clarke 4 , N. 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 patient-reported outcomes of external beam radiation therapy (EBRT) after a high-dose rate brachytherapy boost (HDR-BB) for the treatment of men with intermediate- and high-risk prostate cancer. We aimed to compare patient-reported outcomes following EBRT or EBRT with HDR-BB. Material and Methods Patients diagnosed with intermediate-risk, high-risk or locally advanced prostate cancer in the English National Health Service between April 2014 and September 2016, and subsequently treated with EBRT, were identified from the National Prostate Cancer Audit and mailed a questionnaire 18 months after diagnosis. Patient-reported sexual, urinary, bowel and hormonal function domains using the EPIC-26 (0 – ‘worse function’; 100 – ‘better function’), and generic health-related quality of life (HRQoL) using EQ-5D-5L (0 – ‘death’; 1 – ‘perfect health’), were collected from patient surveys. Comparator groups (EBRT only versus EBRT with HDR-BB) were compared using linear regression, adjusting for patient, tumour and treatment characteristics. Results Of the 13,259 men with intermediate- or high-risk disease (77%) who responded to the patient survey and received EBRT, 12,503 (94.3%) received EBRT only and 756 (5.7%) received HDR-BB. HDR-BB was non-inferior compared to EBRT only for urinary (incontinence), sexual and bowel function, and HRQoL. There was a trend towards clinically worse urinary function (irritative/obstructive domain) for HDR-BB (-6.094 point difference; 95% CI: -8.805 to -3.383) but results were inconclusive in terms of true inferiority (clinically important difference required: -5). Conclusion In a moderate series, HDR-BB is non-inferior compared EBRT only with regard to patient-reported outcomes at 16 months, except for urinary function (irritative/obstructive domain) where inferiority remains inconclusive. PO-1180 Patterns of failure after stereotactic ablative radiotherapy for abdomino-pelvic nodal disease F. Slevin 1 , A. Littlejohns 1 , P. Dickinson 1 , K. Franks 1 , R. Goody 1 , R. Speight 1 , J. Lilley 1 , L. Murray 2 , A. Henry 2 1 Leeds Cancer Centre, Clinical Oncology, Leeds, United Kingdom ; 2 University of Leeds, Clinical Oncology, Leeds, United Kingdom Purpose or Objective There is increasing use of stereotactic ablative radiotherapy (SABR) to treat oligometastatic disease, but there remains limited high-quality evidence to support its use. The purpose of this study was to evaluate patterns of failure and survival endpoints for abdomino-pelvic oligometastatic nodal disease following treatment with SABR.