Abstract
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Objectives Up to 33% of PAC patients develop peripheral venothromboembolic disease (VTE). Those with VTE have more aggressive tumors, thought due to thrombogenic elements in the tumor microenvironment (ME). Animal studies suggest anti-tumor effects of anticoagulants, but human studies are inconsistent, possibly because enriched populations at risk for VTE cannot be assembled. The objectives were: (1) to determine whether metabolic activity of the PAC tumor on initial staging FDG PET-CT predicts aggressiveness of PAC, and (2) whether metabolic activity predicts which patients will develop VTE.
Methods A retrospective study identified 124 patients with PAC with an initial staging FDG PET-CT, measurable primary tumor on CT or MRI and at least 2 years of clinical follow-up. Metabolic activity on FDG PET (SUVmax) and size of primary tumor were correlated with initial stage and overall survival (OS) by Pearson’s correlation. Differences in SUVmax of the primary tumor in patients with and without peripheral VTE or peritumoral vascular thrombosis were compared by 1-way ANOVA analysis of variance.
Results 15/124 patients (12%) developed peripheral VTE, and 39/124 (31%) had peritumoral thrombosis/occlusion. There was a weakly positive correlation between SUVmax and initial stage of PAC (r = 0.25), slightly higher than the correlation between initial tumor size and tumor stage (r = 0.23). However, there was no significant difference in SUVmax between patients who did, or did not, develop peripheral VTE or peritumoral vascular thrombosis. There was a weakly negative correlation between SUVmax and OS (r = -.26).
Conclusions Higher metabolic activity on FDG PET correlates with higher initial stage of PAC and with decreased OS. However, FDG PET did not predict which patients developed VTE. To assemble enriched populations of patients with prominent thrombotic elements in the tumor microenvironment, novel-imaging methods that target ME features may be required.
Research Support Support provided by the Center for Quantitative Cancer Imaging, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT.