Utility of serum cytokeratin 19 fragment (CYFRA 21-1) and carcinoembryonic antigen (CEA) as tumour markers for non-small cell lung cancer.

Serum cytokeratin 19 fragment (CYFRA 21-1) and carcinoembryonic antigen (CEA) levels were determined with an enzyme immunoassay in 51 patients with non-small cell lung cancer (NSCLC), 26 patients with benign lung diseases and 26 normal individuals in order to evaluate their clinical utility in the diagnosis of NSCLC. Patients with NSCLC demonstrated higher serum CYFRA 21-1 and CEA levels than both patients with benign lung diseases and normal group. We used the cut off value which was derived from the 95th percentile value of CYFRA 21-1 and CEA levels in the group of patients with benign lung diseases; CYFRA 21-1 at 3.13 ng/ml and CEA at 7.7 ng/ml. The sensitivity and diagnostic accuracy of CYFRA 21-1 and CEA for the group of NSCLC patients were 66.7 per cent, 76.6 per cent and 35.3 per cent, 55.8 per cent, respectively. When combining CYFRA 21-1 with CEA, the sensitivity and diagnostic accuracy were 68.6 per cent and 66 per cent. These results suggest that CYFRA 21-1 and CEA are useful serum markers for the diagnosis of NSCLC; especially subtype squamous cell and adenocarcinoma, respectively. The usefulness is not enhanced by combining the assay of CYFRA 21-1 and CEA.