Detection of Nodal Metastases by 18F-FDG PET/CT in Apparent Early Stage Ovarian Cancer: a Prospective Study

Background: The rate of nodal metastases in ovarian cancer macroscopically confined to the pelvis is about 15%-20%. Systematic pelvic and aortic lymphadenectomy improves staging but it is associated with increased morbidity and costs. The purpose of this study was to evaluate the role of 18F-FDG PET/CT in the pre-operative nodal metastases detection in ovarian cancer grossly confined to the pelvis.

Methods: From 2006 to 2012, 68 consecutive women with epithelial ovarian cancer confined to the pelvis underwent 18F-FDG PET/CT followed by surgery inclusive of systematic pelvic and aortic lymphadenectomy (SAPL). 18F-FDG PET/CT images were analyzed and correlated to histological examination.

Results: Twenty-six women underwent bilateral and 42 unilateral SAPL with 3165 nodes removed and analyzed. Median number of dissected nodes was 42 (range 16-91). Twelve women (17.6%) had nodal metastases. 18F-FDG PET/CT correctly identified 10 patients with nodal involvement. Sensitivity, specificity, accuracy, positive and negative-predictive value of 18F-FDG PET/CT in detecting nodal metastases were 83.3%, 98.2%, 95.6%, 90.9% and 96.5%, respectively, on overall patient-based, and 75.5%, 99.4%, 98.1%, 87.5% and 98.6%, respectively, on nodal lesion site-based analysis.

Conclusion: 18F-FDG PET/CT is an accurate tool for the detection of nodal metastases. Metabolic imaging could be used to select women who could benefit from systematic lymphadenectomy. The high negative predictive value allows avoidance of SAPL in the vast majority of women, minimizing operative and post surgical complications. Further larger prospective investigation is required to confirm our data.