Value of F-FDG PET/CT Combined With Tumor Markers in the Evaluation of Ascites.

OBJECTIVE

The purpose of this study is to investigate the value of F-FDG PET/CT combined with assessment of tumor markers in serum or ascites for the diagnosing and determining the prognosis of benign and malignant ascites.

MATERIALS AND METHODS

Patients with ascites of unknown cause who underwent evaluation with FDG PET/CT were included in this retrospective study. The maximum standardized uptake value (SUV) and levels of the tumor markers carbohydrate antigen-125 (CA-125) and carcinoembryonic antigen (CEA) in serum and ascites were recorded. The diagnostic values of FDG PET/CT, CEA and CA-125 levels in serum or ascites, and the combination of imaging plus tumor marker assessment were evaluated. Factors that were predictive of survival were also analyzed.

RESULTS

A total of 177 patients were included. Malignant ascites was eventually diagnosed in 104 patients, and benign ascites was diagnosed in the remaining 73 patients. With the use of FDG PET/CT, 44 patients (42.3%) were found to have primary tumors. The sensitivity, specificity, and accuracy of FDG PET/CT were 92.3%, 83.6%, and 88.7%, respectively. CA-125 levels in serum and ascites showed much better sensitivity than did CEA levels, but they showed significantly lower specificity. If the combination of tumor markers and FDG PET/CT was analyzed, the sensitivity, specificity, and accuracy of tumor markers in serum were 96.6%, 78.1%, and 88.7%, and those of tumor markers in ascites were 97.7%, 80.0%, and 90.4%, respectively. Sex may be an important factor affecting survival time (hazard ratio, 0.471; p = 0.004), but age, CEA level, and FDG PET/CT findings could not predict survival.

CONCLUSION

FDG PET/CT combined with assessment of tumor markers, especially CEA, increased the efficacy of diagnosis of ascites of unknown causes. Male sex conferred a poorer prognosis, whereas age, CEA level, and FDG uptake had no predictive significance in patients with malignant ascites.