Optimal cut-off values for CYFRA 21-1 expression in NSCLC patients depend on the presence of benign pulmonary diseases

Background: Serum cytokeratin fragment 21-1 (CYFRA 21-1) expression levels are reported to be useful in the diagnosis of lung cancer, especially non-small cell lung cancer (NSCLC). However, the clinical value of CYFRA 21-1 as a tumor marker remains unclear, and no optimal cut-off value has been determined thus far. The purpose of this study was to establish a potential clinical cut-off value for serum CYFRA 21-1 as a diagnostic marker in patients with NSCLC. Methods: A total of 90 patients with NSCLC, 237 patients with benign pulmonary disease (BPD), and 1296 healthy controls were enrolled in this study. Among BPD there are 84 with chronic obstructive pulmonary disease (COPD), 81 with pneumonia, 38 with tuberculosis and 34 with chronic bronchitis. CYFRA 21-1 was measured in sera with an electrochemiluminescence (ECL) E170 analyzer. Comparisons were conducted using the chi-squared test and the Mann-Whitney test (two-sided). A receiver operating characteristic (ROC) curve was constructed to investigate the diagnostic power of CYFRA 21-1 expression, and the recommended cut-off value was chosen to calculate its sensitivity and specificity. Results: The cut-off values of CYFRA 21-1 in NSCLC by the ROC curve were 4.70 ng/mL when compared with COPD, which was obviously greater than that found with pneumonia (2.79 ng/mL) (P < 0.05), tuberculosis (2.66 ng/mL) (P < 0.05), and chronic bronchitis (3.94 ng/mL) (P < 0.05) patients. Therefore, a cut-off value of 4.24 ng/mL in NSCLC was suggested. Conclusions: The presence of various BPDs may be one of the main reasons that no optimal cut-off value for CYFRA 21-1 expression in NSCLC has been determined previously. (C) 2014 Elsevier B.V. All rights reserved.