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 platinumbased 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 18F-FDG PET-CT scan. Written informed consent was taken. Patients with a positive PET-CT scan were advised ultrasoundguided 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 falsepositive 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.