ESTRO 38 Abstract book

S170 ESTRO 38

SP-0330 Science slam: To breathe or not to breathe. ESTRO Mobility Grant report S. Prcic 1 1 University Medical Centre Maribor, Department of Oncology, Maribor, Slovenia Purpose To learn about Voluntary Deep Inspiration Breath Hold radiotherapy technique. Abstract text Royal Marsden Hospital is one of the first hospitals which has implemented voluntary Deep Inspiration Breath Hold Technique (vDIBH) in a daily clinical practice.Their approach to this technique is unique, very simple and with no additional costs or investments in additional equipment, and therefore it is possible to copy their work onto our Department. My primary goal was to learn how to train patients to breathe during the CT simulation and to learn the procedure of treatment delivery and treatment verification. It was also important to see the whole procedure and do some practical work for better understanding. At the Pre-treatment Unit, I worked together with their radiographers during the CT simulation. Training the breathing technique with patient was of great benefit to further understand the principle of vDIBH. At the Treatment Unit, I was able to see what treatment delivery looks like in clinical practice. Working together with experienced radiographers and with patients, I was able to strengthen and further develop my knowledge gained through CT simulations, and better understand patient setup, treatment delivery and verification. I was also able to discuss outcomes of this technique, patient experience and satisfaction. In a two week period, it was possible to see enough clinical cases and to overcome the challenges of such a technique. SP-0331 Gut microbiota SCFAs modulate dendritic cell antigen presentation and impact radiotherapy Andrea Facciabene 1 , S Rafail 2 , M Uribe-Herranz 3 , C Koumenis 2 1 University Of Pennsylvania, Department Of Radiation Oncology- Rand The Ovarian Canc. Res. Center\R, Philadelphia, Usa 2 Upenn, Radiation Oncology, Philadelphia, Usa 3 Upenn, Radiaiton Oncology, Philadelphia, Usa Abstract text Alterations in gut microbiota impact the pathophysiology of several diseases, including cancer. Radiotherapy (RT), an established curative and palliative cancer treatment, exerts potent immune modulatory effects, inducing tumor-associated antigen (TAA) cross-priming with anti- tumor CD8+ T cell elicitation and abscopal effects. Herein, we tested whether the gut microbiota modulates anti-tumor immune response following RT distal to the gut. Vancomycin, an antibiotic that acts mainly on gram- positive bacteria and is restricted to the gut, potentiated the RT-induced anti-tumor immune response and tumor growth inhibition. This synergy was dependent on TAA cross presentation to cytolytic CD8+ T cells and on IFN-g. Notably, butyrate, a metabolite produced by the vancomycin-depleted gut bacteria, abrogated the vancomycin effect. In conclusion, depletion of vancomycin sensitive bacteria enhances the anti-tumor activity of RT, which has important clinical ramifications. Symposium: The microbiome, inflammation and radiotherapy response

P. Kalendralis 1 , Z. Shi 1 , J. Van Soest 1 , A. Ryczkowski 2 , J. Kaźmierska 2 , J. Malicki 2 , A. Dekker 1 , L. Wee 1 1 Maastro Clinic, Department Of Radiation Oncology Maastro- Grow School For Oncology And Developmental Biology- Maastricht University Medical Centre+- Dr Tanslaan 12- 6229et- Maastricht- The Netherlands, Maastricht, The Netherlands ; 2 Radiotherapy Department Ii- Greater Poland Cancer Center- Poznan- Poland, Radiotherapy Department, Poznan, Poland Abstract text Introduction: Predictive models of radiotherapy (RT) treatment outcomes for head and neck cancer (HNC) patients have clinical value in personalized treatment. Presently, few externally validated models for HNC tumour control and treatment-related toxicity exploit the potential of quantitative image-derived biomarkers (i.e. radiomics) to individually characterize the tumor phenotype. Our primary hypothesis is that adding radiomic features from Planning CT scans improves predictive performance of models for Overall Survival, Xerostomia and Dysphagia, which can be tested by independent external validation between two RT centres. Materials and methods: A “personal health train” architecture (https://www.youtube.com/watch?v=mktAtHmy-FM ) is implemented to connect Maastro Clinic (Maastricht, Netherlands) and the Greater Poland Cancer Centre (GPCC-Poznan, Poland). The workflow of PHT is shown in Figure-1. These centres will independently develop and validate multi-variate prediction models on each other’s patient data without transferring any subject-level information. This methodology could maximally preserve medical data privacy because no individually-identifiable records are shared among centres. Instead, distributed machine learning algorithms shuttle between data sites to fit statistical models of outcome. The data from the two participated centres consist of retrospective clinical observation records and RT Computed Tomography (CT) planning scans approved for research from the Institutional Review Boards (IRBs) of each centre. Results We do not have preliminary results from our study as the workflow will be in progress during the visit to the GPCC. We aim to have local processing of retrospectively collected clinical and imaging data of H&N patients in combination with the development of a clinical prediction model in Poznan’s data preforming distributed validation in MAASTO’s dataset. Furthermore, as an extension of our results we are planning to distribute the final fitted models to a third RT centre for fully independent external validation of the models. Conclusion The collaboration between Maastro and GPCC will potentially increase the sample size for model development, and provide essential alternative cohorts for fully independent external validation of prediction models. In addition, Maastro’s technical infrastructure expertise establishes in return a long-term collaboration in Poland aiming to establish an innovative clinical research into the future.