Prevalence of positive FDG-PET findings in patients with high CEA levels

The purpose of this study was to evaluate the prevalence of positive findings of positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-d-glucose (FDG) in patients with high serum CEA levels. A total of 303 patients who had undergone an FDG-PET scan in our institution with high serum CEA levels were analyzed. The prevalence of positive PET findings was evaluated with regard to a previous history of malignancy, absolute value of CEA levels, and the time course of CEA levels (an increasing or decreasing pattern, a change divided by time (Delta CEA) and doubling time of CEA). Of 303 patients, 232 were confirmed to have malignancy, and the patient-based sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET were 87, 86, 95, 66, and 86%, respectively. There was no statistically significant difference in positive rates according to the history of previous malignancy. The prevalence of PET-positive cases was higher with an increase in absolute CEA levels, and more than 90% of the patients were positive when CEA levels were more than 20 ng/ml. The Delta CEA was significantly higher and the doubling time was significantly shorter in patients with positive results than those with negative results. A high value of serum CEA levels was correlated with a higher prevalence of positive PET findings. FDG-PET scans would be justified in patients with high serum CEA levels, regardless of whether there was or was not a previous history of malignancy.