Carcinoembryonic antigen (CEA) levels in pleural effusions and sera of lung cancer patients.

For determining the value of carcinoembryonic antigen (CEA) levels in diagnosis of malignant tumors of the lung, the CEA levels in 187 specimens of pleural fluid and sera obtained simultaneously from patients with pleural fluid were measured. In all 70 patients with benign diseases, the CEA levels in the effusions were less than the cut-off value of 5 ng/ml (mean +/- SD: 1.44 +/- 1.01 ng/ml). In contrast, in 88 of 117 patients (75.2%) with malignant diseases, the CEA levels in the effusions were over 5 ng/ml (25.3 +/- 24.5 ng/ml) and in 58 of the 117 patients (50.4%), the CEA levels in the serum were values of 5 ng/ml or more (11.9 +/- 18.4 ng/ml). There was a significant correlation between the CEA levels in the effusions and in the sera. The CEA levels in effusions in patients with malignant lung tumors were usually much higher than those in their sera. The incidence of CEA levels of 5 ng/ml or more in both the serum and effusion was highest in the patients with adenocarcinoma. These data indicate that determination of the CEA level in effusions, when done in combination with cytological examinations, may have additional value in diagnosis of lung cancer.