Carcinoembryonic antigen in sputum.

Carcinoembryonic antigen (CEA) levels in sputum from patients with lung cancers (15), other malignancies (7) and non-malignant pulmonary diseases (30) were measured by enzyme immunoassay. The mean value +/- S.E. (ng/ml) of CEA levels in sputum was 3,682 +/- 1,648, 630 +/- 473 and 444 +/- 102, respectively. There was a significant difference in CEA levels between lung cancers and benign pulmonary diseases (p less than 0.01), while no correlation between the serum levels and sputum levels was found. These observations led us to conclude that assay of CEA in sputum appears to be a useful simple test for the diagnosis of bronchopulmonary neoplasms.