Role of ¹⁸F-fluorodeoxy glucose PET-CT in asymptomatic epithelial ovarian cancer with rising serum CA-125: a pilot study

Abstract

Background: We evaluated the role of ¹⁸F-fluorodeoxy glucose (FDG) PET-CT scan in the diagnosis of early relapse in patients with epithelial ovarian cancer (EOC) who were asymptomatic but had a rising serum CA-125 level. Methods: Between May 2006 and July 2008, 16 patients with advanced EOC (stages III and IV) who had achieved complete response after cytoreductive surgery and platinum-based chemotherapy were included. These patients were asymptomatic but had a rising serum CA-125 level with normal physical examination and contrast-enhanced CT scan of the abdomen and pelvis. Patients were evaluated with (18)F-FDG PET-CT scan. Written informed consent was taken. Patients with a positive PET-CT scan were advised ultrasound-guided fine-needle aspiration cytology (FNAC) from the area showing increased uptake. Patients in whom FNAC was negative or inconclusive or those with negative PET-CT scan were followed up closely for the next 6 months with repeat clinical evaluation and CT scan. Results: Fifteen patients (15/16) had a positive PET-CT scan. In 9 patients the positive PET lesion was confirmed on FNAC, while in 5 patients this was confirmed on follow-up CT scan after 6 months. One patient who had a single positive lesion in the pelvis on PET-CT was initially considered false-positive because a follow-up CT scan at 6 months did not show the lesion. However, on regular follow-up after 2 years, she was detected to have an isolated lesion in the PET-positive area which was confirmed on secondary cytoreduction. This patient was considered as true-positive in the current analysis. One patient, who had a negative PET-CT scan and a negative CT scan at 6 months' follow-up was considered true-negative. The sensitivity and specificity of PET-CT scan was 100%. We could confirm positivity on histopathology/FNAC in 10 of the 15 (66.7%) true-positive cases. Conclusion: ¹⁸F-FDG PET-CT scan is a sensitive and specific technique for early diagnosis of relapse in asymptomatic EOC patients with rising CA-125. However, its role in the management of recurrent ovarian cancers needs further evaluation.