Monoclonal antibodies directed against well-known epitopes on cytokeratin (CK) 8, 18 and 19 (Monototal) have been used in the development of a new diagnostic tool for lung cancer. In the mid-1990s, CK 19 fragments (Cyfra 21-1) became popular and widely used for such diagnosis. This is the first study specifically designed to compare these two markers.

The serum levels of CK 8, 18 and 19 were measured using two-site monoclonal/polyclonal immunoradiometric assay kit in 57 healthy adults and 289 patients who were admitted to Seoul National University Hospital from May to September, 2002. The lung cancer group comprised 129 primary lung cancer patients; 116 with non-small cell lung cancer(NSCLC) and 13 with small cell lung cancer (SCLC). The control group comprised 160 non-malignant pulmonary lung disease patients and 57 healthy adults. A total of 166 twin Monototal and Cyfra 21-1 serum assays were obtained; 76 with lung cancer, 70 with non-malignant pulmonary lung disease and 20 healthy adults.

The mean serum value of Monototal was 412.47±455.45U/L in NSCLC, 237.08±145.15U/L in SCLC, 126.54±95.72U/L in non-malignant pulmonary lung disease, and 63.68±31.66U/L in healthy adults. The serum values of the lung cancer groups were significantly higher than those of the control group (p<0.01). Using a cut off value of 188U/L, sensitivity and specificity was 66.4% and 81.9% in NSCLC, and 43.8% and 81.9% in SCLC, respectively. The serum levels of CK 8, 18 and 19 were higher in advanced NSCLC than in early stage disease.

The serum levels of CK 8, 18 and 19 may be useful in the diagnosis of NSCLC.