Effects of chemoradiotherapy on the cardiac and aortic glucose metabolism in patients with advanced non-small cell lung cancer

Background Cardiovascular side-effects of chemoradiotherapy for non-small cell lung cancer (NSCLC) remain a major concern. Insights into vascular changes in atherosclerotic burden and overall disease activity secondary to chemoradiotherapy are useful to predict cardiovascular risk. Computed tomography (CT) calcium score is a biomarker of atherosclerosis while [18F] Fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging can evaluate cardiovascular inflammation. Purpose In patients with advanced NSCLC undergoing repeated [18F] FDG PET/CT imaging, we investigated the effects of chemoradiotherapy on aortic atherosclerotic burden assessed by aortic calcium score, and atherosclerotic disease activity with [18F] FDG uptake. Methods All available oncology PET-CT scans of patients with stage 3B NSCLC from the American College of Radiology Imaging Network (ACRIN 6668) trial were retrieved from the Cancer Imaging Archive and a retrospective analysis was performed. Pre- and post-treatment scans were performed approximately 14 weeks apart. Volumes of interest for the left ventricle, aorta and major non-cardiac organs were manually delineated on all PET-CT scans. Average standard uptake values (SUV), target-to-background ratios (TBR) to aortic blood pool and calcium score were quantified. Aortic PET uptake was analysed for both calcified and non-calcified areas and comparisons before and after treatment scans were performed. Results A total of 26 patients (mean 60±9 years, body-mass index 25±5 kg/m2) met the inclusion criteria. After chemoradiotherapy, calcium score increased by 10% in calcified aortic plaques (p<0.05) (Figure 1A ). [18F]FDG SUVmean uptake was 41% higher in the left ventricular myocardium (p=0.01), but no change was observed in the [18F]FDG uptake of non-cardiac organs (table 1). [18F]FDG TBRmean uptake was 4% higher in calcified aortic plaques (p=0.02), but no change was observed in non-calcified areas of the aorta (Figure 1B,C). Conclusion Metabolic activity is selectively increased in the left ventricular myocardium and calcified aortic atherosclerotic plaques following chemoradiotherapy for NSCLC. Chemoradiotherapy resulted in both an increase in aortic metabolic activity and burden of calcified plaques highlighting an accelerated disease process suggesting an increased cardiovascular risk.