ABSTRACT
BACKGROUND: Cytokeratins are epithelial markers whose expressions are not lost during malignant transformation. The utility of cytokeratin fragment (Cyfra) 21-1, a new tumor marker, was investigated in 110 patients with lung cancer. The aims of this study were to confirm sensitivity of Cyfra 21-1 in detecting non-small cell cancer, to assess the potential relationship between Cyfra 21-1 and disease stage of the lung cancer. METHODS: We measured serum levels of four tumor marker (NSE, CEA, SCC Ag, Cyfra 21-1) in 110 patients with lung cancer. The measurement of serum level of Cyfra 21-1 was performed with a cut off value of 3.3 ng/mL. An immunoradiometric assay was used to detect a fragment of the cytokeratin 19. The patients were grouped according to the stage of the disease and tumor type. RESULTS: Overall sensitivity of Cyfra 21-1 was relatively high (51.8%) than others tumor markers. Sensitivity of this marker was especially high for adenocarcinoma (63.2%) and squamous cell carcinoma (54.1%). In contrast, sensitiviy of Cyfra 21-1 was relatively low for small cell lung carcinoma (40.0%). Serum levels of Cyfra 21-1 were higher in advanced nonsmall cell lung cancer than early stage disease. CONCLUSION: We conclude that Cyfra 21-1 is a sensitive tumor marker of nonsmall cell lung cancer, especially adenocarcinoma and also may be a useful adjunctive marker for disease monitoring.