Abstracts Division 2

44. Tumor metabolic activity is associated with myosteatosis and reduced survival in NSCLC patients

Yan Sun1, Min Deng1, Olivier Gevaert2, Shaimaa Hesham Bakr2, Merel Aberle1, Steven W.M.Olde Damink1,3, Sander S. Rensen1

1
Department of Surgery and NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
2Stanford Center for Biomedical Informatics Research, Department of Medicine, and Department of Biomedical Data Science, Stanford University
3Department of General, Visceral- and Transplantation Surgery, RWTH Aachen University, Germany

Introduction
Cancer cachexia and tumor metabolic activity are both associated with poor survival, but it is unclear how tumors promote development of cachexia. We hypothesized that tumors with higher metabolic activity instigate peripheral metabolic alterations that lead to cachexia, and investigated whether tumor metabolic activity is associated with cachexia-related body composition changes and survival in non-small cell lung cancer (NSCLC).

Methods
A retrospective analysis was performed on a cohort of 121 patients with NSCLC. 18F-fluorodeoxyglucose PET/CT-scans obtained before treatment were used to analyze tumor metabolic activity (standardized uptake value (SUV) and SUV normalized by lean body mass (SUL)) and body composition (skeletal muscle index (SMI), visceral/subcutaneous adipose tissue index (VATI/SATI), myosteatosis) at the L3 level. Subjects were divided into groups with or without myosteatosis based on age- and sex-specific thresholds of the mean Hounsfield units (HU) of muscle area. Mann-Whitney tests, Kaplan-Meier, Cox-regression, and Receiver Operator Characteristics (ROC) curves were used to analyze associations between tumor metabolic activity, myosteatosis, and survival.

Results
The overall prevalence of myosteatosis was 43.0% (52/121). Patients with myosteatosis had shorter survival compared with patients without myosteatosis (median: 25.8 vs. 42.7 months, p=0.03). Myosteatosis was independently associated with shorter overall survival (univariate Cox regression HR=0.482, 95% CI: 0.249-0.933, p=0.03). Muscle radiation attenuation correlated with tumor metabolic activity (SULpeak rs=0.444, p=0.02; SUVpeak rs=0.362, p=0.05), and patients in the myosteatosis group had higher tumor metabolic activity (SULpeak median 8.0, IQR 4.5-12.9, SUVpeak 11.4, 5.0-16.8) than those in the non-myosteatosis group (SULpeak 5.0, 2.0-7.6, p=0.03, SUVpeak 5.8 2.7-9.1, p=0.03, respectively). Tumor metabolic activity parameters predicted the occurrence of myosteatosis in ROC analysis (SULpeak: AUC=0.763, p=0.034, sensitivity/specificity:80%/75%; SUVpeak: AUC=0.744, p=0.038, sensitivity/specificity:85%67%). SMI and VATI were not associated with tumor metabolic activity or survival.  

Conclusions
Higher tumor metabolic activity is associated with myosteatosis and shorter survival in NSCLC.

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