[CYFRA 21-1: a new marker of epidermoid cancer of the bronchi. Comparison with 3 other markers].

Cytokeratins are intermediate filaments of the cytoskeleton that are expressed by bronchial epithelium and its neoplastic counterpart, lung cancer. A new immunoradiometric assay referred to as CYFRA 21-1 makes it possible to titrate in the serum a cytokeratin 19 fragment. This study deals with the sensitivity, specificity and applicability of this serum marker in squamous cell carcinoma. Sera from non malignant pulmonary diseases were taken as controls. In comparison with carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC T-A4) and neuron specific enolase (NSE), CYFRA 21-1 was the most accurate marker. The area under the CYFRA 21-1 ROC curve was significantly greater than those of CEA, SCC T-A4 and NSE. Using a 3.6 ng/ml threshold, as determined by the ROC curve, CYFRA 21-1 was significantly correlated with tumor mass.