Role of FDG PET/CT in the preoperative staging of high-risk clinical early stage endometrial cancer

Objectives: To evaluate: a) the role of FDG PET/CT in the preoperative N-staging of high-risk clinical stage I endometrial cancer; b) the correlation between the metabolic characteristics of endometrial tumor uptake and the presence of lymph-node (LN) metastases. Methods: Sixty-eight high-risk (G2 with deep myometrial invasion, G3, serous and clear-cell carcinoma) clinical stage I endometrial cancer patients (pts) (61.2±13.1 years) underwent preoperative PET/CT scan followed by total hysterectomy, bilateral salpingo-oophorectomy and systematic pelvic lymphadenectomy. PET/CT images were retrospectively analyzed and correlated to histological findings. Maximal and mean standardized uptake value (SUVmax, SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG) of endometrial lesions were calculated. Results: PET/CT resulted negative at pelvic LNs in 58/68 pts (57 TN, 1 FN) and positive in 10/68 pts (9 TP, 1 FP). On pt-based analysis, sensitivity, specificity, accuracy, negative and positive predictive value of PET/CT in detecting pelvic LN metastases were 90%, 98%, 97%, 98%, 90%, respectively. A significant correlation was found between the presence of LN metastases and SUVmax (p=0.03), MTV (p=0.01), TLG (p=0.004) of the primary tumor, respectively, while no significant correlation was obtained for SUVmean. Conclusions: In high-risk clinical stage I endometrial cancer: a) FDG PET/CT is an accurate tool for the nodal status assessment. Its high negative predictive value (98%) could be useful in selecting pts who may benefit from lymphadenectomy; b) SUVmax, MTV and TLG of the primary tumor are significantly correlated to LN metastases