ESTRO 2025 - Abstract Book

S1307

Clinical - Lung

ESTRO 2025

radiotherapy. Relationships between dose parameters - mean heart dose (MHD), heart V10 (HV10), mean lung dose (MLD), lung V5 (LV5) – and measurements of longitudinal systolic RV function and global RV function at each time point were assessed using linear mixed models. Effect modification of the dose-response relationship by comorbidities was evaluated by adding interaction terms to the model. Results: The study population consisted of 54 (26%) women, 126 (60%) patients with oesophageal cancer, 58 (28%) with cardiac comorbidity, and 40 (19%) with COPD. Later loss of longitudinal systolic RV contraction speed (S’RV) depended on heart dose ( Table 1 ), while early global RV dysfunction (increase in TEI index) was associated with lung dose ( Table 2 ). Co-morbidity acted as an effect modifier for multiple dose-effect relations. In patients with pre-existing heart disease, a decrease in longitudinal systolic contraction (TAPSE) one year after radiotherapy was associated with heart dose ( Table 1 ). Meanwhile, in patients with COPD, heart dose was linked to global systolic RV function (FAC) at 3 months ( Table 2 ) and S’RV at 6 months ( Table 1 ). Additionally, lung dose was associated with TAPSE and FAC at 6 weeks ( Table 1 ), and with TEI index at 3 months ( Table 2 ).