Lab Med Online.  2015 Jul;5(3):143-148. 10.3343/lmo.2015.5.3.143.

Diagnostic Utility of Serum Cytokeratin Fragment 21-1 in Patients with Lung Cancer

  • 1Department of Laboratory Medicine, Konyang University Hospital, Konyang University College of Medicine, Daejeon, Korea.


Lung cancer is the most lethal malignant neoplasm in the world. Serum cytokeratin fragment 21-1 (Cyfra 21-1) is a valuable tumor marker for detection of lung cancer, and it has good sensitivity and specificity. The aim of this study was to investigate the diagnostic value of Cyfra 21-1 levels in patients with lung cancer.
We retrospectively reviewed 814 samples from 169 patients with lung cancer, 124 patients with benign pulmonary diseases, and 521 normal controls from health check-up clinic. Serum Cyfra 21-1 levels were determined with Architect CYFRA 21-1 kit (Abbott, USA) using Architect i2000 analyzer.
Median levels and interquartile ranges for Cyfra 21-1 in patients with lung cancer (non-small cell lung cancer: 3.16 [1.98, 9.00] ng/mL, small cell lung cancer: 3.32 [2.07, 5.20] ng/mL) were higher than those in patients with benign pulmonary diseases (1.50 [1.17, 2.17] ng/mL; P<0.01) and in normal controls (1.26 [0.93, 1.75] ng/mL; P<0.01). Sensitivity, specificity, positive predictive value, and negative predictive value for Cyfra 21-1 were 70.4%, 81.2%, 49.6%, and 91.3%, respectively. The area under the curve for Cyfra 21-1 was 0.839 (95% confidence interval, 0.802-0.877).
We concluded that Cyfra 21-1 may be useful in the diagnosis of lung cancer.


Cyfra 21-1; Lung cancer; Tumor marker
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