ESTRO 2020 Abstract book

S58 ESTRO 2020

more severe late xerostomia was more likely in patients with a smaller ADC rise in those glands, this pattern met statistical significance in the left PG only. This signal will be evaluated further in a larger dataset on completion of the MeRInO study. As strategies to reduce toxicity after H&N RT continue to be investigated, serial evaluation of ADC in salivary glands during treatment may allow a biologically adaptive treatment strategy for those identified to be most at risk of late severe toxicity. OC-0109 Cardiovascular risk assessment based on cardiac calcifications on breast RT planning CT scans R. Gal 1 , I. Išgum 2,3,4 , S.G.M. Van Velzen 2,4 , M.J. Emaus 1 , D.H.J.G. Van den Bongaard 5 , M.L. Gregorowitsch 1 , E.L.A. Blezer 1 , S.A.M. Gernaat 6 , N. Lessmann 2 , M.G.A. Sattler 7 , A.J. Teske 8 , J. Penninkhof 7 , H. Meijer 9 , J.J. Van Tol- Geerdink 9 , J. Pignol 10 , J. Verloop 11 , H.M. Verkooijen 1 1 University Medical Center Utrecht- University of Utrecht, Division of Imaging and Oncology, Utrecht, The Netherlands ; 2 University Medical Center Utrecht- University of Utrecht, Image Sciences Institute, Utrecht, The Netherlands ; 3 Amsterdam University Medical Center, Department of Radiology and Nuclear Medicine, Amsterdam, The Netherlands ; 4 Amsterdam University Medical Center, Department of Biomedical Engineering and Physics, Amsterdam, The Netherlands ; 5 Amsterdam University Medical Center, Department of Radiation Oncology, Amsterdam, The Netherlands ; 6 Karolinska Institutet, Department of Oncology-Pathology, Stockholm, Sweden ; 7 Erasmus MC Cancer Institute, Department of Radiation Oncology, Rotterdam, The Netherlands ; 8 University Medical Center Utrecht- University of Utrecht, Department of Cardiology, Utrecht, The Netherlands ; 9 Radboudumc, Department of Radiation Oncology, Nijmegen, The Netherlands ; 10 Dalhousie University, Department of Radiation Oncology, Halifax- Nova Scotia, Canada ; 11 Netherlands Comprehensive Cancer Organisation, Department of Research, Utrecht, The Netherlands Purpose or Objective With improved breast cancer survival, the prevention of treatment-induced toxicity is becoming increasingly important. Adjuvant treatments including anthracyclines, targeted and radiotherapy are associated with an increased risk of cardiovascular disease (CVD). Breast cancer patients with pre-existing CVD risk factors have the highest risk of treatment induced cardiotoxicity. Coronary artery calcium (CAC) is a strong independent CVD risk factor and can be quantified on dedicated cardiac computed tomography (CT) scans. Before adjuvant treatment with radiotherapy, a CT scan of the chest is performed for radiotherapy treatment planning. These CT scans allow routinely assessing CAC scores in breast cancer patients, and thereby detecting patients at increased CVD risk. In the Bragatston study, we evaluate the association between automatically measured CAC on radiotherapy planning CT scans and the risk of CVD events in breast cancer patients. Material and Methods In this multicenter historical cohort study, breast cancer patients receiving radiotherapy between 2005-16 were included. CAC scores were automatically extracted from the planning CT scan using an in house developed deep learning algorithm and categorized following the five-level scale Agatston classification (0, 1-10, 11-100, 101-399, >400 units). Tumor and treatment characteristics were obtained from the Netherlands Cancer Registry, the Netherlands Comprehensive Cancer Organisation. Data on occurrence of CVD were obtained from Dutch Hospital Data (DHD) and the National Cause of Death Register, Statistics Netherlands. Cox proportional hazard regression models were used to evaluate the association between CAC scores

Conclusion A non-statistically significant trend was demonstrated between toxicity and change in ADC in all PGs and SMGs –