RESUMO
BACKGROUND: Cytokeratins were subdivided into 20 different cytokeratins. It is known that cytokeratin 19 is particularly abundant in carcinoma of the lung. METHOD: A sandwich enzyme-linked immunosorbent assay called CYFRA 21-1, combining two monoclonal antibodies directed specifically aganist cytokeratin 19 was done by ES-300(Boehringer Mannheim, Germany). We investigated the diagnostic value of the new tumor marker CYFRA 21-1 in lung cancer in comparison to carcinoembryonic antigen(CEA) and neuron specific enolase(NSE) in the pilot study on 39 serum samples from lung cancer (17 squamous cell cancer, 11 adenocarcinoma, 11 small cell carcinoma) and 51 benign lung diseases and 41 normal healthy persons. RESULTS: Postulating a specificity 95% versus benign lung disease and healthy group, the diagnostic sensitivity of CYFRA 21-1 in lung cnacer independent of histologic type was 43.6% whereas CEA was 48.7% and NSE was 30.8%. The diagnostic sensitivity is increased to 69.2% by combining CYFRA 21-1 with CEA. Classifying the lung carcinomas following their histologic type, squamous cell carcinomas proved to possess the highest CYFRA 21-1 sensitivity(CYFRA 21-1 47.1%, CEA 23.5%, NSE 11.8%) and the combination with CEA 52.9% could not markedly increase the number of true-positive test results. In adenocarcinoma, CEA possessed the highest sensitivity (81.8%) whereas CYFRA 21-1 was 45.5% and NSE was 9.1%. In small cell carcinoma of lung, NSE possessed the highest sensitivity(81.8%) whereas CYFRA 21-1 was 36.4% and CEA was 54.5%. CONCLUSION: This study indicates that CYFRA 21-1 has a potential as a new marker for squamous cell lung cancer. If histologic type is unknown at the time of primary diagnosis. the combined determination of CYFRA 21-1 and CEA showed the best discrimination between benign and malignant lung disease.