Abstract Book

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doses per fraction. Lower dose-per-fraction regimens allow for reoxygenation and corresponding sensitization, but lose effectiveness due to proliferation. Conclusion; Effective consolidation therapy after CCRT has been developed and locoregional control is more important than ever. Dose-escalation should be executed in a patient-specific manner with preferably hypofractionated regimens. The combination of fractionated RT and SBRT might be a smart strategy compared to fractionated dose escalation studies. High doses to the mediastinal structures can be avoided using IMRT. [1] Scott J et al. Durvalumab after Chemoradiotherapy in Stage III Non–Small-Cell Lung Cancer. N Engl J Med 2017; 377:1919-1929 [2] Randomized Trial of SABR vs Conventional Radiotherapy for Inoperable Stage I Non-Small Cell Lung Cancer: TROG 09.02 (CHISEL) [3] Sun Y et al. Serum MicroRNA Signature Predicts Response to High-Dose Radiotehrapy in Locally Advanced Non-Small-Cell Lung cancer. Int J Radiat Oncol Biol Phys. 2017 Sep 4 [4] Jeong J et al. Clin Cancer Res. Modeling the Cellular Response of Lung Cancer to Radiation Therapy for a Broad Range of Fractionation Schedules. 2017 Sep 15;23(18):5469-5479. SP-0553 What’s new in the management of high risk prostate cancer patients in 2018: the role of Imaging R. Renard Penna 1 , P. Maksud 2 1 Institut Curie Ensemble Hospitalier service formation, Imagery, Paris cedex 05, France 2 Pitié salpétrière, Nuclear medecine, paris, France Abstract text Objetives This course will identify the relevance of MRI and modern imaging concepts for the management of high risk prostate cancer We will explore the impact of prostate MRI, targeted biopsies and biomarkers for optimizing detection and characterization of high risk prostate cancers, We also present the most current information regarding the performance of prostate MRI for local staging and the impact for treatment. We will discuss about modern imaging concepts for the preoperative lymph node staging (PET CT and PET MR) and new tracers as C11 choline, F18 fluciclovine, and Prostate Specific Membrane Antigen (PSMA) labeled tests. Learning objectives: · Impact of prostate MRI and targeted Biopsies in characterization of high risk prostate cancer· Optimal staging of patients with high risk prostate cancer by understanding the performance of prostate MRI for evaluation of extra-capsular extension or seminal vesicles involvement· Apply the most modern imaging concepts for lymph node staging. · Impact of PET/CT and PET/MRI in detection of micro- metastases· Role of 68GA-PSMA, 18F-PSMA-1007 and new tracers in improving staging of high risk prostate cancer SP-0554 New irradiation options P. Hoskin 1 1 Mount Vernon Hospital, Cancer Centre, Northwood Middlesex, United Kingdom Abstract text Radiotherapy continues to have a major role in the treatment of high risk prostate cancer. Established techniques use either brachytherapy or external beam photon therapy alone or in combination. Innovations in Symposium: What’s new in the management of high risk prostate cancer patients in 2018?

dose, fractionation and technique continue to redefine state of the art radiation delivery in this setting which currently would mandate the use of static or rotational IMRT and daily IGRT. The advent of the MR linac will provide further insights into inter- and intrafraction verification requirements A dose response for biochemical control of prostate cancer has been long recognised and there is now considerable level 1 evidence that hypofractionated schedules over 4 to 5 weeks are equivalent to longer conventional fractionation. Dose escalation remains a goal and this may be optimally achieved by combining external beam and brachytherapy. Extreme hypofractionation using fraction sizes of >5Gy demands a high level of technical accuracy both in volume definition and delivery. The emergence of stereotactic techniques for prostate cancer has enabled external beam therapy to achieve this. Phase III trials comparing this to conventional external beam schedules are now completed and the results eagerly awaited. In high risk disease the role of pelvic node irradiation remains uncertain. Whilst practised in many centres for Gleason score 8-10 cancers it is recognised that to date Level 1 evidence for this approach is lacking and further trials are endeavouring to address this important question. Modern imaging has enabled greater understanding of the distribution of cancer within the prostate gland with the concept of a radiological index or dominant lesion. Focal boosts have been evaluated both in external beam and brachytherapy providing another avenue for dose escalation within acceptable toxicity profiles. SP-0556 Outcome prediction models – training and validation I.R. Vogelius 1 1 Vogelius Ivan Richter, Academic Physics, Frederiksberg, Denmark Abstract text Outcome models should ideally fulfill the follwing four criteria to be applied in the clinic: 1) face validity, ie. the models should be credible and meaningful to the treating physician. 2) internal validity, ie. the model should provide a good fit to the data on which it is built. We will spend some time on discussing how to perform and present model fits in a clear and concise manner such that the fulfillment of this point is adequately conveyed to the critical reader of your work. Criterion no 3) is external valudity, ie. the model ability to be applied in datasets outside of the training cohort. We will go through successful and not-so-successfull examples from literature and discuss how to impove your chances of fulfilling criterion three. Finally, and most demanding, the models should have 4) clinical utility. While criterion four is outside of the scope of my talk, it is important that the modeler has clinical utility top-of-mind throughout the entire process. Arguably, it is less wastefull to fail an attempt to build a model with potential clinical utility than suceeding in externally validating a model which does not stand a chance to pass the clinical utility bar. The interested participant may benefit from readin Wyatt and Altman’s SP-0555 The surgeon point of view A.Briganti Fondazione Centro San Raffaele, Milano, Italy Abstract not received Symposium: Outcome prediction models for RT indications - development, validation, acceptance, commissioning and application