ESTRO 2020 Abstract Book

S620 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.

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