Diagnostic Accuracy of Preoperative Metabolic 18F-FDG PET/CT Parameters for Patients with Endometrial Cancer Treated with Postoperative Radiation Therapy

Objective: This study aimed to evaluate the diagnostic accuracy of preoperative 18F-fluorodeoxy- glucose (FDG) positron emission tomography/computed tomography (PET/CT) metabolic parameters for the prediction of risk factors and detection of lymph node metastasis (LNM) in patients with endometrial cancer. Material and Methods: This study included 26 patients with endometrioid carcinoma who underwent preoperative PET/CT and treated with adjuvant local radiotherapy. The maximum standard uptake value of the tumor (SUVmax-T), SUVmax of the pelvic and/or para-aortic LNs, metabolic tumor volume (MTV), and tumor lesion glycolysis (TLG) with cut-off values of 30-40% were calculated. International Federation of Gynecology and Obstetrics stages 3 and 4, highgrade disease, lymphovascular invasion (LVI), cervical involvement (CI), and myometrial invasion (MI) ≥50% were established as high-risk features. Disease-free survival and overall survival were analyzed in comparison with 18F-FDG PET/CT parameters. Results: SUVmax-T was only associated with tumor diameter (p=0.01). It was not correlated with MI, high-grade disease, CI, or LNM. With SUVmax-P ≥2.81 as a cut-off value, the sensitivity, specificity, and accuracy in the detection of LNM were high (90%, 83.3%, 71.4%, respectively). For LNM, the mean MTV-30 (p=0.021), TLG-30 (p=0.030), and SUVmax-P (p=0.009) were significant predictors. According to the regression analysis, MTV-40 (p=0.043) was an independent predictor of LNM, and LVI (p=0.037) was the only significant predictor of MI. MTV-30 was a significant predictor of CI (p=0.04). Conclusion: SUVmax-P, MTV, and TLG cut-off values, to predict LN metastases, increase diagnostic accuracy for EC.