ESTRO 2024 - Abstract Book

S1575

Clinical - Lung

ESTRO 2024

compared to higher GPA scores. To our knowledge, this study offers the largest independent external validation of the latest iteration of the GPA index in Europe. Our data suggests the GPA index is a useful tool in a UK setting.

Keywords: brain metastasis, gamma knife radiosurgery

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Cardiac effects after lung and oesophageal cancer radiotherapy

Arno C. Hessels 1 , Umut Fidan 1 , Robin Wijsman 1 , Emmy Slager 1 , Jan Bussink 2 , Anthonie L. Duijnhouwer 3 , Tineke P. Willems 4 , Elke S. Hoendermis 5 , Johannes A. Langendijk 1 , Christina T. Muijs 1 , Peter van Luijk 1 1 University Medical Centre Groningen, Radiation Oncology, Groningen, Netherlands. 2 Radboud University Medical Centre, Radiation Oncology, Nijmegen, Netherlands. 3 Radboud University Medical Centre, Cardiology, Nijmegen, Netherlands. 4 University Medical Centre Groningen, Radiology, Groningen, Netherlands. 5 University Medical Centre Groningen, Cardiology, Groningen, Netherlands

Purpose/Objective:

Thoracic radiotherapy involves heart and lung radiation doses, resulting in damage and adverse effects. Although the exact mechanism is not known, heart and lung doses have even been associated with reduced survival. In rats, heart and lung irradiation resulted in reduced diastolic function and pulmonary arterial hypertension. Therefore, the ongoing CLARIFY study aims to test the hypothesis that early changes to the heart also occur in patients treated with thoracic radiotherapy. In the present interim analysis we hypothesize (1) that early changes in cardiac function and morphology can be seen after irradiation for lung or oesophageal cancer, and (2) that both heart and lung radiation dose contribute to these changes.

Material/Methods:

For the current analysis 129 participants of the CLARIFY study, treated for lung (49) and oesophageal (80) cancer between September 2018 and February 2023, were selected. Cardiac ultrasound measurements performed at baseline and at 6, and 52 weeks after radiotherapy were analysed. Follow-up at 1 year after radiotherapy was available for 66 patients. To identify coherently changing ultrasound parameters, Principal Component Analysis (PCA) was performed. PCA summarized the 28 ultrasound variables into 6 principal components (PCs), representing changes from baseline of various aspects of cardiac function and morphology. The relation between radiation dose (mean heart dose (MHD), mean lung dose (MLD), volume of the lung receiving ≥5 Gy (LV5)) and the PC scores was evaluated using linear regression. The influence of age, gender, induction chemotherapy, COPD, cardiovascular comorbidity, diabetes and ACE inhibitor use on these dose-response relationships was investigated through stratified analysis and multivariable regression.

Results: