ESTRO 38 Abstract book

S443 ESTRO 38

Conclusion The analysis of the SPARK trial primary outcome measure showed that the KIM real-time target tracking is clinically useful in improving the prostate and rectal dose in the presence of target motion. PO-0843 Toxicity of a brachytherapy boost for prostate cancer patients L. Bokhorst 1 , S. Van der Pol 2 , C. Niël 2 , C. Hoekstra 2 1 UMC Utrecht, Radiation Oncology, Utrecht, The Netherlands ; 2 Radiotherapiegroep, Radiation Oncology, Deventer, The Netherlands Purpose or Objective To compare potency, urinary, and gastro-intestinal toxicity in men with prostate cancer receiving brachytherapy, external beam radiation therapy (EBRT), or EBRT with a brachytherapy boost (both low and high From 2000-2018 all patients treated for prostate cancer in our institute were regularly followed and toxicity was prospectively collected at each follow-up visit using predefined questionnaires. For this analysis we compared IPSS score (>=20 versus <20), potency score (>=5 versus <5, on a 0 to 8 point scale with 8 being completely impotent and a score >=5 being comparable with a CTCAE >=3), urinary incontinence (>1 pad use per day), and rectal soiling (any pad use) between men receiving either brachytherapy alone (I-125, 145Gy), EBRT (>=76Gy), EBRT + LDR brachytherapy (50Gy + 100/110Gy), and EBRT + HDR brachytherapy (68Gy + 1x10-15Gy). Men receiving salvage treatment were excluded from this analysis. Results During follow-up 3291 patients were treated (59% EBRT, 23% brachytherapy, 10% EBRT + LDR, 8% EBRT + HDR) received a total of 28877 follow-up visits (1000 patients were followed more than 7 years). Data completeness differed per questionnaire but ranged from 77% for urinary incontinence up to 86% for potency scores. The largest difference in IPSS scores were seen in the first year after treatment, with more and longer urinary problems for men receiving LDR brachytherapy with or without EBRT versus EBRT alone of combined with HDR brachytherapy (figure 1). After 2.5 and 4.5 years of follow-up overall urinary incontinence was 2.7% and 3.6% respectively, overall impotency (in men receiving no (neo)adjuvant hormonal therapy) was 38.3% and 49.9% respectively, and rectal soiling was reported by 0.5% and 0.5% respectively. There were no significant differences in potency score, urinary incontinence of rectal soiling between the different treatment groups during follow-up (table 1). dose rate (LDR/HDR)). Material and Methods

Conclusion Adding a brachytherapy boost (either LDR and HDR) did not increase long-term potency urinary, or gastrointestinal toxicity as compared to EBRT or brachytherapy (LDR) alone. PO-0844 Target motion mitigation and dose painting in prostate cancer SBRT: results from a Phase II study C. Greco 1 , O. Pares 1 , N. Pimentel 1 , V. Louro 1 , B. Nunes 1 , J. Sroom 1 , S. Viera 1 , D. Mateus 1 , Z. Fuks 1 1 Fundação Champalimaud, Radiation Oncology, Lisboa, Portugal Purpose or Objective to report biochemical, MR response and patient-reported quality of life (QoL) after extreme SBRT (9Gyx5) in patients with histologically proven organ-confined adenocarcinoma of the prostate using target motion mitigation and OARs dose painting. Material and Methods Between May 2013 and September 2017, 207 men were enrolled in an IRB-approved phase II prospective study to receive 45Gy in 5 consecutive daily fractions of 9Gy with critical tissue sparing (urethra, urogenital diaphragm and neurovascular bundles). Treatment planning was based on VMAT-IGRT with a negative dose-painting technique to fulfil organ-specific dose-volume constraints The CTV and