CLINICAL USEFULNESS OF CYFRA ASSAY IN DIAGNOSING LUNG-CANCER - MEASUREMENT OF SERUM CYTOKERATIN FRAGMENT

We evaluated the diagnostic usefulness of measurement of the soluble c ytokeratin 19 fragment, a new tumor marker, in 391 patients with lung cancer and in 424 patients with benign lung diseases. Serum concentrat ions of cytokeratin 19 fragment were measured by a sandwich ELISA (CYF RA). The cut-off value was defined as 3.5 ng/ml, which is associated w ith a specificity of 85% for benign lung diseases. CYFRA had a high se nsitivity (57.5%) in all subjects with lung carcinoma, and had a highe r sensitivity for squamous cell carcinoma (73.1%, n=141) than squamous cell carcinoma-related antigen (61.0%). CYFRA was associated with a r elatively high sensitivity (42.1%) in early-stage squamous cell carcin oma (stage I, based on the classification of the Japan Lung Cancer Soc iety), but the CYFRA titer was higher in advanced squamous cell carcin oma than in early stage squamous cell carcinoma. Our findings suggest that CYFRA is potentially useful for diagnosis and monitoring of. lung carcinoma, especially for squamous cell carcinoma.