ESTRO 2023 - Abstract Book

S480

Sunday 14 May 2023

ESTRO 2023

Conclusion We highlighted that the predisposition to GI toxicity requires an understanding of the gut MB both at the ecological and at the functional level. Our analysis suggests that an altered ion homeostasis at the level of bacterial communities might predispose pts to the onset of GI toxicity. The predictive features identified are the relative abundance of genera Faecalibacterium, Bacteroides, Parabacteroides, Alistipes, Prevotella and Phascolarctobaterium and seem to generalize prediction beyond sequencing technology and platforms and overcome potential bias associated with the ethnic origin of patients (at least for what concern western European countries). The study opens up concrete prospects for the use of baseline faecal samples in the clinical practice to improve pre-RT toxicity risk assessment and RT planning optimization. MicroLearner was funded under the Call for the Promotion of Institutional Research INT-year 2016, 5 × 1000 Italian Ministry of Health. MicBioRadio was funded by FRRB, ID 2721017 1 Queen's University Belfast, Patrick G Johnston Centre for Cancer Research, Belfast, United Kingdom; 2 Queen's University Belfast, Wellcome-Wolfson Institute For Experimental Medicine, Belfast, United Kingdom; 3 Belfast City Hospital, Northern Ireland Cancer Centre, Belfast, United Kingdom Purpose or Objective Despite modern advances, radiation cardiotoxicity (RC) is common among patients with lung and oesophageal cancer, including infarction and arrhythmia. The pathophysiology explaining these processes is a combination of endothelial dysfunction, connective tissue dysregulation and cardiomyocyte necrosis. Dose and/or volume dependence for RC is lacking but recently the dose received by the base region has been correlated with worse survival. Statin therapy has been shown to reduce short-term functional effects of whole-heart irradiation in murine models, most likely owing to their pleiotropic antioxidant and anti-inflammatory properties on the target tissues listed. Here a 50-week study serially assessing functional parameters in mice receiving base-targeted heart irradiation, with concomitant statin therapy, was conducted. Materials and Methods Female C57BL/6 mice (n=58) received 16Gy/1# to the cranial third of the heart using image-guidance on a small animal radiotherapy research platform, or atorvastatin therapy alone, or both. The animals were monitored with serial echo- and electrocardiography (ECG) every 10 weeks, and blood, and heart collections at 10, 30 and 50 weeks. Serum atrial natriuretic peptide (ANP) was analysed from blood retrieved at the point of animal tissue collection. Results At 30 and 40 weeks a statistically significant reduction in the left ventricular (LV) fractional shortening was observed in the animals receiving radiation alone, compared to the animals receiving concomitant atorvastatin (p=0.018, p=0.00, Figure 1). A similar trend was observed in LV ejection fraction also, in keeping with LV systolic dysfunction at these time-points. OC-0598 Mitigative potential of statin therapy in base-mediated radiation cardiotoxicity G. Walls 1 , M. Ghita 1 , R. Kuburas 1 , K. Edgar 2 , C. Watson 2 , D. Grieve 2 , A. Cole 3 , K. Butterworth 1