Predictive value of 18F-fluorodeoxyglucose accumulation in visceral fat activity to detect colorectal cancer metastases (prospective observational cohort study)

<ns3:p><ns3:bold>Background: </ns3:bold>To evaluate functional visceral adipose tissue (VAT) activity assessed by <ns3:sup>18</ns3:sup>F-fluorodeoxyglucose (<ns3:sup>18</ns3:sup>F-FDG) positron emission tomography/computed tomography (PET/CT) as a predictive factor of metastases in colorectal cancer (CRC) patients.</ns3:p><ns3:p> <ns3:bold>Methods:</ns3:bold> We reviewed study protocols and PET/CT data of 534 CRC patients; 474 patients were subsequently excluded for various reasons. The remaining 60 patients with histologically confirmed adenocarcinoma were then prospectively assessed and were exposed to <ns3:sup>18</ns3:sup>F-FDG PET/CT after a surgical treatment and chemoradiotherapy. Age, histology, stage, and tumor grade data were recorded. Functional VAT activity was verified with maximum standardized uptake value (SUV<ns3:sub>max</ns3:sub>) using <ns3:sup>18</ns3:sup>F-FDG PET/CT and tested as a predictive factor of later metastases in eight subdomains of abdominal regions (RE – epigastric region, RLH – left hypochondriac region, RRL – right lumbar region, RU – umbilical region, RLL – left lumbar region, RRI – right inguinal region, RP – hypogastric (pubic) region, RLI – left inguinal region) and pelvic cavity (P) in the adjusted regression models. In addition, we studied the best areas under the curve (AUC) for SUV<ns3:sub>max</ns3:sub> with the corresponding sensitivity (Se) and specificity (Sp).</ns3:p><ns3:p> <ns3:bold>Results:</ns3:bold> In both adjusted for age regression models and receiver operating characteristic (ROC) curve analysis, <ns3:sup>18</ns3:sup>F-FDG accumulation in RLH (cut-off SUV<ns3:sub>max</ns3:sub> 0.74; Se 75%; Sp 61%; AUC 0.668; p=0.049), RU (cut-off SUV<ns3:sub>max</ns3:sub> 0.78; Se 69%; Sp 61%; AUC 0.679; p=0.035), RRL (cut-off SUV<ns3:sub>max</ns3:sub> 1.05; Se 69%; Sp 77%; AUC 0.682; p=0.032) and RRI (cut-off SUV<ns3:sub>max</ns3:sub> 0.85; Se 63%; Sp 61%; AUC 0.672; p=0.043) could predict later metastases in CRC patients, as opposed to age, sex, primary tumor location, tumor grade and histology.</ns3:p><ns3:p> <ns3:bold>Conclusions:</ns3:bold> Functional VAT activity was importantly related to later metastases in CRC patients and can be used as their predictive factor.</ns3:p>