Clinical Significance Of Thymidine Kinase1Expressions And Mesothelial Cell Counts In The Differential Diagnosis Of Pleural Effusions

Objective To compare the efficacy of thymidine kinase1, a novel tumor marker, andmesothelial cell counts by liquid-based technology with ordinary makers in diagnosis ofmalignant and benign pleural effusions.Methods105patients were screened in this study.50cases were with malignant pleuraleffusion,44cases were with tuberculous pleural effusion,11cases were withpara-pneumonic effusions. Mesothelial cells and nucleated cells in pleural effusion wascounted on the slides made by liquid-based technology. The proportion of mesothelialcells was calculated from count results. Effusion TK1and CEA concentration wasdetected by chemiluminescence. LDH concentration in the effusion was analyzed bycontinuous monitoring method. Mann-Whitney U test and Kruskal-Wallis H test wereenrolled in comparison between groups; multiple comparisons were correct byBonferroni’s correction; receiver operating characteristic curve and area under the curvewere used in assessing the diagnostic value of each index. Two areas under the curve ofreceiver operating characteristic curve were compared by Hanley&McNeil method.Combined diagnostic models were established and the predicted probabilities ofdiscriminant analysis were used in creating receiver operating characteristic curves.Results When used as the indicators of benign and malignant pleural effusions, the AUCs of effusion TK1concentration, CEA content and mesothelial cell counts were0.899,0.845,0.692, separately. The AUCs of TK1and CEA concentration were greaterthan the AUC of mesothelial cell counts, the difference was statistically significant(P<0.017, by Bonferroni correction), no significant difference shown between the AUCsof TK1and CEA concentration (P>0.017, by Bonferroni correction). Set the cut-offvalue at4.07pmol/L and5.43ng/mL, the sensitivity and specificity in diagnosingmalignant pleural effusion of pleural TK1was90.00%and83.64%, while pleural CEAwas68.00%and94.55%. The effusion TK1concentration was more sensitive in MPEsdiagnosing than CEA, but less specific and poor in identifying histological type ofprimary tumor. The AUC of ROC curve of mesothelial cell counts in differentiatingbenign and malignant pleural effusion was only0.692, set the value which mademaximum Youden index as cut-off value, the sensitivity was only62.00%, specificity85.45%, however, mesothelial cell counts in identification of para-pneumonic effusionand tuberculous pleural effusion in benign pleural effusion got a significantly high AUCof ROC curve at0.947, and its sensitivity and specificity was90.91%and88.64%whenthe cut-off value was0.04. Several diagnosis models were also established bydiscriminant analysis, the sensitivity, specificity or AUC of ROC curve was higher thanthe original by using predicted probabilities as new indexs to identify benign andmalignant pleural effusion or tuberculous effusion and parapneumonic effusion. Thesediagnosis models could be chosen according to the needs of the clinical practice.Conclusion TK1is a novel sensitivity marker in differentiating benign and malignantpleural effusion, mesothelial cell counts with liquid-based technology in the differentialof para-pneumonic effusion and tuberculous pleural effusion have high diagnostic value.