Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/ Computed Tomography in the Detection of Ovarian Cancer Recurrence in Patients with Elevated Serum Ca-125 Levels and Whether the Recurrence appears by Conventional Imaging

Abstract

Introduction: We aimed in this study to evaluate the benefit of Fluorine-18 (18F) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in the detection of ovarian cancer recurrence in a selected patient group who had elevated serum Ca-125 levels and whether the recurrence appears by conventional imaging.

Material and Method: A total of 39 female patients (mean age: 59±12.3) who underwent 18F-FDG PET/CT for restaging of ovarian cancer due to of elevated serum Ca-125 levels were retrospectively included to this study. 18F-FDG PET/CT imaging have been performed for searching possible disease recurrence in 24 patients who had normal or undetermined abdominal CT or pelvic MRI (Group 1) and evaluating to extent of disease in 15 patients who had abnormal abdominal CT or pelvic MRI (Group 2). Disease recurrence was confirmed by histopathological examination of surgical procedures or clinical follow-up data for at least 6 months period.

Results: The mean period between the completion of initial treatment and 18F-FDG PET/CT was 2.6±1.4 years. In 33 of the 39 patients (82%), recurrent disease was developed during the follow-up period. Of the 33 patients with recurrent disease, 6 (18%) were confirmed by histopathological examination, while in 27 (82%) were documented by clinical follow-up. The mean Ca-125 level and the SUVmax value of group 1 were 509 U/ml (range 50.3-6544 U/ml) and 12.26±4.9 (range 0-21.7), respectively. Overall sensitivity and specificity of 18F-FDG PET/CT in group 1 were quantified as 94% and 75%, respectively. The mean Ca-125 level and mean SUVmax value of group 2 at the time of 18F-FDG PET/CT scans were calculated as 358 U/ml (range 40.6-1233U/ml) and 11.4 ± 4.53 (range 4.5-20.1), respectively. Disease recurrence of 14 (93%) patients was correctly identified by 18F-FDG PET/CT. The sensitivity of 18F-FDG PET/CT in the detection of disease recurrence of group 2 was quantified as 100%. Specificity could not quantified due to absence of TN and FP results.

Conclusions: 18F-FDG PET/CT has higher sensitivity and specificity in the detection recurrent ovarian cancer than serum Ca-125 levels and ceCT alone. The addition of 18F-FDG PET/CT to Ca-125 and ceCT improves the sensitivity of the evaluation of disease extension.