Preoperative PET/CT provided information on standardized uptake value (SUV) and volumetric parameters, particularly total lesion glycolysis (TLG), that represented strong predictors of tumor characteristics, including myometrial invasion (MI) and cervical stromal invasion (CSI), according to study results published in Molecular Imaging And Radionuclide Therapy.

Investigators assessed the diagnostic value of pre-operative PET/CT in endometrial cancer staging and establish the volumetric PET parameters that are accurate indicators of histopathological tumor characteristics. They retrospectively analyzed PET/CT data from 66 patients with endometrial cancer (mean age, 63.56±10.11; 87.9% postmenopausal), dividing patients into low- and high-risk groups according to the European Society for Medical Oncology criteria. Information on the maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary lesion and pathological lymph nodes was obtained, as was information on International Federation of Gynecology and Obstetrics (FIGO) classifications, histopathology, myometrial invasion (MI) depth, lymph node metastasis (LNM), cervical stromal invasion (CSI), and tumor size. Data were analyzed from January 2016 to November 2017.

TLG was the most valuable parameter in distinguishing risk groups, according to the researchers. SUVmax, TLG, and MTV values varied significantly between high-risk and low-risk groups. Specifically, PET/CT had 90% sensitivity, 96.3% specificity, 81.8% positive predictive value, 98.1% negative predictive value, and 95.45% accuracy in evaluating LNM. Patients with non-endometrioid pathology had higher MTV and TLG values than those with endometrioid. Among patients with deep MI, the SUVmax, MTV, and TLG were higher than in those with superficial MI, and those with CSI had greater TLG values than those without CSI. MTV and TLG values were higher in those with LNM than in those without LNM. The study team reported a significant difference for TLG, MTV, and SUVmax values between patients with FIGO stage I-II versus patients with FIGO stage III and higher.

In addition to the indication that volumetric parameters from 18F-FDG PET/CT can predict tumor characteristics in the preoperative period, the study results show that these parameters may impact treatment choices, including surgical approach, by supplying more precise risk classification, the authors noted.