ESTRO 2022 - Abstract Book

S481

Abstract book

ESTRO 2022

0.2 and 0.9 for bladder wall, rectal wall, sigmoid wall, ureter and lumbosacral plexus, respectively ; with deformable registration: 0.8, 0.8, 0.5, 0.8 and 0.9, respectively. Median DVH values within deformable registration were : bladder wall V65=43.5%, V50=66.5%, rectal wall V70=5.6% , V60=30%, V50=51%, sigmoid wall V40=43%, ureter D0.5cc=69 Gy, lumbosacral plexus D0.5cc=60 Gy. Compared to QUANTEC recommendations, this corresponded to median relative spread of: bladder wall V65= -13%, V50= +33%, rectal wall V70= -72%, V60= -14%, V50= +2%, sigmoid wall V40= +7.5%, lumbosacral plexus D0.5cc= +20%. With median follow-up of 62.5 months after PLN-RT, 5 patients (15%) had grade ≥ 2 toxicity, among them 2 had grade 3 urinary incontinence or obstruction. Neither ureter stenosis nor lumbosacral plexopathy were noted. No significant correlation was found between grade ≥ 2 toxicities and specific dose accumulation. Five patients received additionnal pelvic bone or nodal SBRT after PLN-RT, one of them developped grade 2 sigmoid stenosis and the other grade 2 sacral fracture. Conclusion Cumulative DVH at low dose ( ≤ 50Gy) exceeded the commonly recommended values for the pelvic OAR but without notable late toxicity, while standard limits were respected at higher dose. Our data aim to provide a prospectively-validated support for the dosimetric process of salvage PLN-RT following prior P-RT. T. Elumalai 1,2 , R. Portner 3 , N.B.G. Mariam 3 , T. Young 4 , S. Hughes 5 , K. Wickramasinghe 6 , R. Bhana 7 , K.T. Jayaprakash 8 , M. Sabar 2 , A. Hudson 9 , P. Hoskin 10 , H. Mistry 11 , A. Choudhury 11 1 The Christie NHS Foundation trust, Clinical oncology, Manchester, United Kingdom; 2 Cambridge University Hospitals NHS Foundation Trust, Clinical oncology, Cambridge, United Kingdom; 3 The Christie NHS foundation trust, Clinical oncology, Manchester, United Kingdom; 4 Guy’s and St Thomas’ NHS Foundation Trust, Clinical Oncology, London, United Kingdom; 5 Guy’s and St Thomas’ NHS Foundation Trust, Clinical oncology, London, United Kingdom; 6 University Hospitals of North Midlands NHS Trust, Clinical oncology, Stoke on Trent, United Kingdom; 7 University Hospitals of North Midlands NHS Trust, Clinical oncology, Stoke on trent, United Kingdom; 8 Cambridge University Hospitals NHS Foundation Trust, Clinical oncology, cambridge, United Kingdom; 9 The Christie NHS Foundation trust, Clinical oncology, Mancheste, United Kingdom; 10 The University of Manchester, Division of cancer sciences, Manchester, United Kingdom; 11 The University of manchester, Division of cancer sciences, Manchester, United Kingdom Purpose or Objective Node positive prostate cancer (N+PCa) represents a heterogeneous cohort of patients, and the management strategy for these men remains controversial. Patients with N+PCa are often grouped into either locally advanced or metastatic PCa with little supporting evidence for either approach. We aimed to evaluate patterns of care and outcomes across four UK centres and analyse prognostic variables and treatment parameters for impact on clinical outcomes. Materials and Methods Data on men with clinically diagnosed N+PCa treated between 2011 and 2019 were collected retrospectively. All of them had baseline CT scan to confirm the presence of pelvic nodes. Baseline prognostic variables included: age, performance status (PS) prostate-specific antigen (PSA), Gleason score, tumour stage (T2/T3 vs T4) and nodal disease burden. Data on therapeutic options collected included: androgen deprivation therapy (ADT), radiotherapy (RT), surgery and chemotherapy. Outcome parameters collected included overall survival (= time from the date of diagnosis to death due to any cause), bPFS (biochemical PSA progression free survival) (biochemical progression = PSA nadir + 2) and rPFS (radiological progression-free survival). Descriptive statistics were performed, and survival was estimated using the Kaplan-Meier method. A Cox-proportional hazards model was used for multivariate analysis. Results Data on 337 men with a median follow-up time of 48 months (45-51) were collected. 96% of men were treated with ADT, with 20% receiving ADT alone. 32% of men received lifelong ADT and 64% had ADT for 2-3 years. 70% of men had RT, with 38% receiving RT to the prostate and pelvic nodes. 22% of men had docetaxel chemotherapy with 16% receiving docetaxel chemotherapy in addition to prostate RT (figure 1). MO-0555 Radiotherapy for node-positive prostate cancer correlates with improved survival