Diagnostic utility of serum and pleural fluid carcinoembryonic antigen, and cytokeratin 19 fragments in patients with effusion from nonsmall cell lung cancer.

AIMS: To assess the diagnostic value of CEA and CYFRA 21-1 (cytokeratin 19 fragments) in serum and pleural fluid in non small cell lung cancer with malignant pleural effusion (MPE).

SETTINGS AND DESIGN: Two subsets of patients were recruited with lymphocytic exudative effusion, one subset constituted diagnosed patients of NSCLC with malignant pleural effusion and the other subset of constituted with Tubercular pleural effusion.

MATERIALS AND METHODS: CYFRA 21-1 and CEA levels were measured using Electrochemilumiscence Immunoassay (ECLIA). The test principle used the Sandwich method. For both the tests, results are determined via a calibration curve which is instrument specifically generated by 2 - point calibration and a master curve provided via reagent barcode.

STATISTICAL ANALYSIS USED: All data are expressed as means ± SD and percentage. All the parametric variables were analysed by student-t test where as non parametric variables were compared by Mann-Whitney U-test Statistical significance was accepted for P values < 0.05. Software used were SPSS 11.5, and MS excel 2007. In order to compare the performance of the tumor markers, receiver operating characteristic (ROC) curves were constructed and compared with area under the curve (AUC). The threshold for each marker was selected based on the best diagnostic efficacy having achieved equilibrium between sensitivity and specificity.

RESULTS: In cases serum CYFRA21-1 levels had mean value of 34.1 ± 29.9 with a range of 1.6-128.3 where as in controls serum CYFRA21-1 levels had mean value of 1.9 ± 1.0 with a range of 0.5-4.7. In cases serum CEA levels had mean value of 24.9 ± 47.3 with a range of 1.0, 267.9 where as in controls serum CEA levels had mean value of 1.9 ± 1.4 with a range of 0.2-6.8. The difference in the means of serum CYFRA 21-l (P = 0.000) and CEA (P = 0.046) were statistically significant. In cases pleural fluid CYFRA21-1 levels had mean value of 160.1 ± 177.1 with a range of 5.4-517.2 where as in controls pleural fluid CYFRA21-1 levels had mean value of 15.9 ± 5.7 with a range of 7.2-29.6. In cases CEA pleural fluid levels had mean value of 89.8 ± 207.4 with a range of 1.0-861.2 where as in controls CEA levels had mean value of 2.5 ± 2.3 with a range of 1-8.9. The difference in the means of CYERA 21-1 (P = 0.001) between cases and controls is statistically significant.

CONCLUSIONS: CYFRA21-1 (serum - pleural fluid) is a sensitive marker for NSCLC with sensitivity of 96.7%, highest of any combination [Serum (CYFRA 21-1 - CEA). CEA (Serum + Pleural Fluid), Pleural Fluid (CYFRA 21-1 + CEA)] and specificity of 77.8%. Levels of CYFRA21-l (serum + pleural fluid) are increased in malignant pleural effusion, so it is better to be used in suspicious malignant pleural effusion showing negative cytology, particularly in the absence of a visible tumor and or unsuitability for invasive procedure.