| Malignant tumor remains a life-threatening disease in the world, pleural effusions are common complications of malignancy. Clinically, the diagnosis of malignant pleural effusions and the differentiation between malignant and paramalignant or nonmalignant effusions are sometimes difficult. In recent years, several tumor-associated markers have been studied in pleural effusion fluid. Careinoembryonic antigen (CEA), one of the tumor markers mostly studied in pleural fluid, has one of the highest sensitivity. Telomerase is a ribonucleoprotein that synthesizes telomeric DNA onto chromosomal ends using its complementary RNA sequence as a template. The expression of telomerase activity and the stabilization of telomere length appear to be correlated with the attainment of immortality of various tumor cells. DNA flow cytometry provides a new tool for the discrimination of cytologically benign and equivocal effusions.In this study, telomerase activity of 53 pleural effusions were detected by using the THAI' assay, combining with the analysis of the DNA ploidy S-phase fraction and DNA index by the flow cytometry and thedetermination of CEA levels. The main purpose of the present study was to evaluate the diagnostic capacity in differentiation of pleural fluid of three different tumor markers, telomerase activity, DNA ploidy and CEA.Patients and MethodsFrom December 1999 to December 2000, 53 pleural fluid samples were collected from consecutive, unselected patients undergoing a therapeutic or diagnostic thoracentesis at our hospital and were examined for routine, biochemistry, LDH, cytology, telomerase activity, CEA, and DNA ploidy. Some of those patients received fibrobronchoscopic examination, transcutaneous pleural biopsy and lymph nodes biopsy. According to the finial diagnosis achieved, patients were classified into three groups. Group 1 consisted of 16 patients with definite malignant pleural effusions. Group 2 consisted of 18 patients with suspicious malignant pleural effusions, patients were classified into this group because of effusions associated with a known malignancy in which cytologic examination of pleural fluid and pathologic testing of percutaneous pleural biopsy could not demonstrate metastases. Group 3 consisted of 19 patients with nonmalignant pleural effusions.Pleural fluid samples were obtained from patients underwent thoracentesis. Telomerase activity was assayed according to TRAP PCR-ELLISA. DNA ploidy analysis was performs by flow cytometry and the histograms were evaluated. CEA was based on the Microparticle Enzyme Irnmunoassay (MEIA) technology.All the testing data V,XTO statistically analyzed by SPSS R)R WINDOWS 10.0 SOFTWARE KIT.Results and DiscussionThe telomerase activity was assayed quantitatively and qualitatively. DNA ploidy was analyzed diploid and aneuploid by histograms and DNA index and S-phase fraction were calculated. The cutoff value of CEA was(lOug/ml.The tumor markers with the highest specif icity(94. 7%) for malignancy were telomerase activity, although with the same sensitivity (73.5%) as CEA. The positive predictive value , negative predictive value and total accuracy were 0.96, 0.82, 85. 7% and 0. 81, 0.84, 82. 9% respectively. The highest individual sensitivity got to 100% when telomerase and CEA marker were combined, with a specificity of 78. 9%..There were significant differences of telomerase activity, DNAploidy and CEA between definite malignant pleural effusion vsnon-malignant effusion and suspicious malignant effusion vsnon-malignant effusion by Pearson Chi-Square test .CEA detection was superior to telomerase activity and DNA ploidy in the diagnostic value of definite malignant effusion by the analysis of ROC curve, whereas telomerase activity was better than CEA and DNA ploidy in the diagnostic value of suspicious malignant effusion. Both telomerase activity and CEA were of great value in the differential diagnosis of pleural effusion.Conclusion1. Telomerase activity and CEA are of value in the differential diag...
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