Diagnostic algorithm based on ratio of ascites-serum tumor markers is superior to tumor markers in the differentiation of benign ascites from malignant ascites.

Background: Differential diagnosis between benign ascites and malignant ascites remains challenging in clinical practice, the aim of our study is to determine the differential value of the ratio of ascitic-serum tumor markers between benign ascites and malignant ascites.

Methods: 418 patients with new-onset ascites were retrospectively enrolled in this study. The pertinent data of patients enrolled were collected; diagnostic value of tumor markers, ascites-serum tumor marker ratio, and diagnostic algorithm based on ascitic tumor markers and ascites-serum tumor marker ratio in patients with ascites were investigated.

Results: 81.25% of the patients with benign ascites had low (<1) ratio of ascites-serum tumor markers (Max [A/S CEA, A/S CA15-3, A/S CA19-9]); and 91.88% of patients with benign ascites had the ratio of ascites-serum tumor marker less than 1.5. On the other hand, 94.96% of the patients with malignant ascites had high (≥1) ratio of ascites-serum tumor markers; and 97.29% of patients with malignant ascites had the ratio of ascites-serum tumor markers more than 0.67. Finally, diagnostic algorithm based on ascitic tumor markers and ascites-serum tumor marker ratio showed 96.37% of the sensitivity, and 94.37% of the accuracy in the diagnosis of malignant ascites, while ascitic tumor markers with a sensitivity of 78.29%, and an accuracy of 84.93%.

Conclusions: Diagnostic algorithm based on ascitic tumor markers and ascites-serum tumor marker ratio exhibited an excellent performance in distinguishing benign and malignant ascites, which should be recommended in patients with new-onset ascites in clinical practice.