18F- FDG PET/CT-derived parameters predict clinical stage and prognosis of esophageal cancer.

Although <sup>18</sup> F- FDG PET/CT is validated in baseline workup of esophageal cancer to detect distant metastases, it remains underused in assessing local staging and biology of the primary tumor. This study aimed to evaluate the association between <sup>18</sup> F- FDG PET/CT-derived parameters of esophageal cancer, and its clinico-pathological features and prognosis. All patients (n = 86) with esophageal adenocarcinoma or squamous cell cancer operated between 2005 and 2014 were analyzed. Linear regression was used to identify clinico-pathologic features of esophageal cancer associated with the tumor's maximal Standardized Uptake Value (SUV <sub>max</sub> ), Total Lesion Glycolysis (TLG) and Metabolic Tumor Volume (MTV). ROC curve analysis was performed to precise the optimal cutoff of each variable associated with a locally advanced (cT3/4) status, long-term survival and recurrence. Kaplan Meier curves and Cox regression were used for survival analyses. High baseline SUV <sub>max</sub> was associated with cT3/4 status and middle-third tumor location, TLG with a cT3/4 and cN+ status, whereas MTV only with active smoking. A cT3/4 status was significantly predicted by a SUV <sub>max</sub> > 8.25 g/mL (p < 0.001), TLG > 41.7 (p < 0.001) and MTV > 10.70 cm <sup>3</sup> (p < 0.01) whereas a SUV <sub>max</sub> > 12.7 g/mL was associated with an early tumor recurrence and a poor disease-free survival (median 13 versus 56 months, p = 0.030), particularly in squamous cell cancer. Baseline <sup>18</sup> F- FDG PET/CT has a high predictive value of preoperative cT stage, as its parameters SUV <sub>max</sub> , TLG and MTV can predict a locally advanced tumor with high accuracy. A SUV <sub>max</sub> > 12.7 g/mL may herald early tumor recurrence and poor disease-free survival