[F-18-FDG positron emission tomography in the diagnosis of ovarian recurrence. Comparison with CT scan and CA 125]

Abstract

Objective: The aim of this study was to evaluate the clinical utility of FDG-PET for detecting recurrent disease in patients with ovarian cancer.

Material and methods: Twenty-one FDG-PET studies performed in 19 patients who had previously undergone surgery and chemotherapy for ovarian cancer were reviewed retrospectively. In a maximum interval of one week regarding the FDG-PET study, computed tomography (CT) was performed and CA-125 levels were measured. In 16 cases the relapse suspicion was due to elevation of the tumor marker CA125 and in 5 cases it was due to CT. PET images were obtained at 45 min after the intravenous injection of 370 MBq of FDG. The results of the visual interpretation were compared with the CA125 levels and the images of the CT, and related to the definitive diagnosis. Recurrence was confirmed in 19/21 cases, by means of pathological findings (11 cases) and clinical follow-up for a median of 11 months in the others.

Results: Recurrence was confirmed in 16 cases with increased CA-125 and the tumor marker was true-negative in 2 disease free cases, but there were 3 false-negative results (sensitivity of 84 % and accuracy of 86 %). CT correctly identified 9 cases with recurrence, but it was false-negative in 10 cases and false-positive in 2 disease free patients (sensitivity of 47 % and accuracy of 43 %). FDG-PET correctly detected the 19 cases with recurrence but it was false-positive in 2 cases with a sensitivity of 100 % and accuracy of 90 %. In 3 patients with CA125 false-negative and 10 patients with false-negative CT, FDG-PET was positive and recurrence was confirmed.

Conclusion: These preliminary results suggest that in the follow-up of patients with ovarian cancer FDG-PET could detect recurrence with higher accuracy than CT, and even with higher sensitivity than the tumor marker CA125, being useful at the same time to locate the recurrence when the tumor marker is positive.