ESTRO 2020 Abstract Book

S621 ESTRO 2020

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.

Material and Methods Single-centre, retrospective casenote review of 57 patients and 72 abdomino-pelvic lesions treated with 30 Gy in 3 or 5 fractions (5 fractions used for re-irradiation cases) between 2016-18. Survival endpoints were calculated using the Kaplan-Meier method and univariable Cox regression analyses were performed to test association of patient, disease and treatment factors with survival endpoints. Results Primary tumour site was prostate, colorectal and other in 37, 14 and 6 patients respectively. Median follow-up duration was 15.6 months (range 1-39.4 months). PET-CT staging was used in 30/37 prostate and 12/14 colorectal patients. 39, 13 and 4 patients had 1, 2 and 3 lesions treated respectively. 1 year local control (LC), overall survival (OS) and progression-free survival (PFS) was 96.3%, 100% and 80.5% for prostate patients and 66.7%, 90% and 51.9% for colorectal patients respectively. 1 year PFS following SABR with concurrent androgen deprivation therapy was 86% versus 67% without ( p =0.044). No factors evaluated using univariable Cox regression analyses were found to be statistically significant. A trend to inferior PFS was observed where SABR was not the first intervention for relapsed disease (1 year PFS 44.9% versus 78.1%, p =0.2). Further relapses occurred adjacent to the treated node in 5 patients and in distant metastatic sites in 13 patients. For prostate cancer, side of T3 primary disease was associated with side of nodal relapse on chi square analysis 1 year OS and LC rates were good, especially for prostate cancer. Acknowledging the modest follow up duration, PFS was comparable with published results. Most patients relapsed with distant metastases, which reflects the limitations of current staging investigations. 5 patients relapsed adjacent to the treated node, which often precludes further SABR. This suggests a strategy of concurrent treatment of the nodal chain/whole pelvis alongside SABR to the involved node could be advantageous. PO-1181 Metastasis-Directed Therapy influence in clinical outcomes of oligorrecurrent prostate cancer A. Gonzalez Lopez 1 , D. Büchser 1 , F. Suarez 1 , E. Mayrata 1 , F. Casquero 1 , P. Bilbao 1 , A. Gomez-Iturriaga 1 1 Hospital de Cruces, Radiation Oncology, Barakaldo, Spain Purpose or Objective Interest in metastases-directed therapy (MDT) in oligometastatic cancer is increasing due to various studies suggesting this approach may improve clinical outcomes. The aim of this study was to analyze the influence of single or repeated MDT in clinical response of oligorrecurrent From 2012 to 2019, 200 oligometastatic lesions were treated in 77 PCa patients with oligometastatic disease at our institution. Seven patients were de novo M1 disease and there were 7 castrate-resistant (CR) PCa at first MDT. After biochemical failure (bF), patients underwent repeated Choline-PET-CT, and patients with oligorecurrent metastases were offered subsequent MDTs. Descriptive statistics were used to summarize patient characteristics. The Kaplan-Meier method assessed rates of bF-free survival (bFFS) and castrate-resistant-free survival (CRFS). Univariate and multivariate analysis were done to evaluate the influence of prognostic factors in clinical outcomes. Results At first MDT, 159 lesions were treated (71.4% nodal, 26% bone, 2.6% combination of both). Median PSA before Ch- PET was 6.21 ng/mL with a median doubling-time of 8.71 mo. MDT modalities were intensity-modulated ( p =0.008). Conclusion prostate cancer (PCa). Material and Methods