Clinical value of baseline 18F-FDG PET/CT in soft tissue sarcomas.

BACKGROUND The use of 18F-FDG Positron emission tomography/Computed tomography (PET/CT) in the initial staging of many cancers is clearly established. Most soft tissue sarcoma (STS) has a high affinity for 18F-FDG, which is why 18F-FDG PET/CT has been proposed as a non-invasive method, useful in diagnosis and follow-up. The standardized uptake value values (SUV), the volume-based metabolic parameters MTV (metabolic tumor volume), and TLG (total lesion glycolysis) determine tumor viability and provide its total volume and the total activity of metabolically active tumor cells. The histological grade is the most important predictor of metastases and mortality associated with STS, and a significant relationship between the metabolic parameters of 18F-FDG PET/CT and the histological grade has been described. METHODS A retrospective study was conducted on STS patients, who had histological grade according to the FNCLCC (Federation Nationale des Centres de Lutte Contre Le Cancer) criteria, as well as a baseline PET/CT. SUV (SUVmax, SUVmean, and SUVpeak), MTV, and TLG were quantified. A T-student test was performed to establish the relationship between the metabolic biomarkers and the histological grade. Their usefulness as predictors of the histological grade was verified using receiver operator characteristic (ROC) curves. A survival function study was performed using the Kaplan-Meier method. To assess the prognostic utility of the metabolic biomarkers we use the Log-Rank method. RESULTS The SUV values were useful to discriminate high-grade STS. We found a significant relationship between the histological grade and the SUV values. SUVmax, SUVpeak, MTV, and TLG were predictors of overall survival (OS). There were no significant differences in the OS for the SUVmean, or in the disease-free survival (DFS) for SUVmax, SUVmean, SUVpeak, MTV, and TLG. CONCLUSIONS The SUVmax, SUVmean, and SUVpeak values correlate with the HG and are useful to discriminate high-grade from low-grade STS. Patients with high SUVmax, SUVpeak, MTV, and TLG have a significantly lower OS.