| BACKGROUNDMalignant ascites is defined as abnormal accumulation of fluid in the peritoneal cavity as a consequence of cancer and presents a difficult clinical problem causing discomfort and distress to many patients in the advanced stages of their disease. It accounts for around 10% of all cases of ascites and occurs in association with a variety of neoplasmas. The presence of malignant ascites in patients with neoplastic disease frequently heralds the terminal phase of cancer. It is a poor prognostic indicator, with a median survival time ranging from 78 days to 3.1 months accompanied with a poor quality of life. During the last few years our understanding of the etiology of malignant ascites has changed. This new information modifies our therapeutic approaches of neoplastic effusions.Reasonable management is depended on accurate diagnosis. The reasons that can cause ascites are variety. Cirrhosis, congestive heart failure, nephrosis, tuberculosis, pancreatitis, and peritonitis from pyogenic organisms can produce intraabdominal fluid accumulation. Thus, differentiating between malignant and nonmalignant ascites is very important for the clinical practice. Abdominal paracentesis with analysis of the ascitic fluid should be used in most cases where there is doubt. The aspirated fluid should undergo microscopic, chemical, and cytologic analysis. Cell blocks from centrifuged specimens of ascitic fluid should be submitted for cytology. Unfortunately, though with high specificity, ascitic fluid cytology is diagnostic in only 50%～60%. The new assays with higher sensitivity and specificity are needed. Tumor marker, especially carcinoembryonic antigen(CEA) can be useful in differential diagnosis of the reasons in malignant ascites, although it lack specificity. DNA ploidy analysis performed by flow cytometry is a new technology with high accuracy in measurement of the cells from different origin. It has been widely used in research work and clinical practice.OBJECTIVETo investigate the differential diagnostic significance of DNA ploidy analysis and carcinoembryonic antigen assay in the malignant and benign ascites.MATERIALS AND METHODSFlow cytometry (FCM) was used for DNA ploidy analysis and enzyme linked immunosorbent assay(ELISA) for CEA assay in 34 malignant ascites which had been made a definite diagnosis by pathohistologic or cytologic methodes. As a control, 39 nonmalignant ascites were evaluated at the same time. Follow the instructions manual' suggestion, we use 5μg/L as the cutoff of CEA regardless in serum or in ascitic fluid. If the CEA value >5μg/L or the ascites/serum CEA ratios >1, the CEA assay was defined as positive. If a aneuploidy was detected, the result of the DNA ploidy analysis was defined as positive. Between the two group, the CEA concentration and the ascites/serum CEA ratios and the DNA index were evaluated by student t test; while the positive rate was evaluated by chi-square test by SAS statistics software 9.0.RESULTS1.The CEA concentration and the ascites/serum CEA ratios and DNA index in malignant ascites group were all higher than that in benign ascites group.2.The positive rates of serum CEA, ascitic CEA, ascites/serum CEA ratios and aneuploidy were all higher than that in benign ascites group.3.The sensitivity and specificity of serum CEA, ascitic CEA, ascites/serum CEA ratios and aneuploidy in diagnosis malignant ascites were50%, 79.49%; 55.88%, 87.18%; 44.12%, 94.87%; 76.47%, 84.61% respectively.4.We also evaluated differential diagnosis value of the combinations between aneuploidy and CEA assay. The sensitivity and specificity of the aneuploidy combined to serum CEA, ascitic CEA, ascites/serum CEA ratios were 85.29%, 100%;88.24%, 100%; 85.29%, 100% respectively. All the combination assay had the higher sensitivity or specificity than any of the single assay.CONCLUSIONOur study confirmed the differential diagnosis value of the CEA assay and the DNA ploidy analysis in malignant ascites, and the combination of CEA assay and the DNA ploidy analysis can improve the sensitivity and specificity of the effect of differential diagnosis of malignant ascites from benign ascites. |
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