Abstract: Objective To discuss the role of tumour marker in differentiating malignant pleural effusion from benign ones.Method Pleural and serum levels of cytokeratin 19 fragment(CYFRA21.1)and carcinoembryonic antigen(CEA)were determined in 108 patients with pleural effusions(68 malignant and 40 tuberculous).Result Pleural and serum CYFRA21.1 and CEA levels were significantly higher in the cancer group than that in the tuberculous group.In the cancer group,CYFRA21.1 levels in pleural fluid did not differ significantly from that in the serum.CYFRA21.1 levels showed some false positive reaction in the pleural fluid of the patients with tuberculous effusions.Conclusion Combining the CEA test with CYFRA21.1 analysis appears to be very useful in differentiating malignant pleural effusion from the benign ones.

Key words: CYFRA21.1, CEA, Pleural effusion, Tumour marker