ABSTRACT
<p><b>OBJECTIVE</b>To explore the diagnostic value of carcinoembryonic antigen (CEA) and cytokeratin-19-fragment (CYFRA21-1) in lung cancer patients.</p><p><b>METHODS</b>The levels of serum CEA and CYFRA21-1 were measured in 102 patients with lung cancer, 45 patients with benign lung disease and 36 health controls by electrochemiluminescence.</p><p><b>RESULTS</b>The level of serum CEA and positive rate [(25.77 ± 15.34) ng/ml, 47.1%] were significantly higher in the lung cancer group than that in the benign lung disease group [(4.67 ± 2.21) ml, 7.7%; P < 0.05] and controls [(3.98 ± 3.00) ng/ml, 3.8%; P < 0.05], The level of serum CYFRA21-1 and positive rate [(14.08 ± 8.34) ng/ml, 62.7%] were also significantly higher in the lung cancer group than that in the benign lung disease group [(3.27 ± 2.87) ml, 7.7%; P < 0.05] and controls [(2.69 ± 2.02 ng/ml, 3.8%; P < 0.05]. The difference of level of CEA and CYFRA21-1 between the benign lung disease group and controls was statistically not significant (P > 0.05). Both tumor markers were increased to a different degree in the lung cancer patients at various TNM stages [(CEA: stage II (17.78 ± 8.71) ng/ml, stage III (25.84 ± 7.34) ng/ml, stage IV (34.85 ± 6.99) ng/ml; and CYFRA21-1: stage II (10.05 ± 6.76) ng/ml, stage III (15.93 ± 6.66) ng/ml, stage IV (22.78 ± 4.12) ng/ml]. Combined use of both makers showed a significant higher sensitivity (77.5% vs. 47.1%, 62.8%), but reduced specificity (86.8% vs. 94.0%, 95.6%), and not significantly changed accuracy (83.5% vs. 77.1%, 83.8%) in the diagnosis of lung cancer.</p><p><b>CONCLUSIONS</b>CEA and CYFRA21-1 employed separately are helpful in the diagnosis of lung cancer. Combined detection of these two tumor markers can improve the positivity for diagnosis of lung cancer.</p>