[18F]FDG PET/CT and CA-125 in the evaluation of ovarian cancer relapse or persistence: is there any correlation?

Background: Ovarian cancer relapse can be diagnosed by serum tumor markers measurements and 18F-fluorodoxyglucose positron emission tomography/computed tomography ([18F]FDG PET/CT) findings. The aim of our study was to analyze the potential relationship between cancer antigen 125 (CA-125) and PET/CT results in patients affected by ovarian cancer.

Material and methods: Ninety-two [18F]FDG PET/CT scans in sixty-one patients with diagnosis of ovarian cancer were analyzed and compared to CA-125 values. PET/CT results were compared to other imaging modalities, histology or follow-up data in order to define its diagnostic accuracy. PET/CT studies were analyzed qualitatively and semiquantitatively by measuring the maximum and mean standardized uptake value body weight max (SUVbw max, SUVbw mean), maximum SUV lean body mass (SUVlbm), maximum SUV body surface area (SUVbsa), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of hypermetabolic lesions. All measurements were compared with CA-125 values.

Results: Twenty PET/CT studies were true negative, sixty-three true positive, five false positive and four false negative with sensitivity of 94%, specificity of 80%, negative predictive value of 83%, positive predictive value of 93% and accuracy of 90%. CA-125 levels were significantly correlated with PET/CT results and all PET/CT semiquantitative parameters. CA-125 cutoff values of 17 UI/mL is the best compromise between sensitivity and specificity in discriminating between positive and negative PET/CT result.

Conclusions: [18F]FDG PET/CT has good accuracy in evaluating patients with relapse or persistance of ovarian cancer. CA-125 levels were significantly correlated with metabolic PET/CT parameters.