Serum carcinoembryonic antigen correlates with severity of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the commonest idiopathic interstitial pneumonia and carries a poor prognosis. Epidemiological evidence suggests that patients with IPF have an increased risk of developing lung cancer. Carcinoembryonic antigen (CEA) has a close association with epithelial malignancy. The aim of this study was to evaluate serum CEA concentrations in patients with IPF and to perform correlation with pulmonary function.

Serum CEA concentrations were measured by two-site sequential chemiluminescent immunometric assay in 41 non-smoking patients with IPF. Patients with a history of gastrointestinal tract malignancy or other disorder known to be associated with raised serum CEA were excluded.

A total of 41 patients were evaluated. The mean (±standard deviation) age of patients was 73 ± 7 years. The mean (±standard deviation) forced vital capacity was 88 ± 20% of predicted, and the mean (±standard deviation) diffusing factor for carbon monoxide (DLco) was 52 ± 19% of predicted. Twenty-one (51%) patients had a serum CEA concentration higher than upper limit of the normal range (0-5 ng/mL). CEA concentration was significantly negatively correlated with lung function (P = 0.005; R(2) = 0.20 for forced vital capacity and P = 0.006; R(2) = 0.20 for DLco). Raised CEA level also correlated significantly with the extent of fibrosis. A lung biopsy specimen from a patient with IPF demonstrated strong staining for CEA in metaplastic epithelium lining the honeycombed cysts and respiratory bronchioles.

Serum CEA concentration is elevated in approximately half of patients with IPF and is correlated with disease severity. Immunohistochemical staining reveals that CEA localizes to metaplastic epithelium lining honeycombed bronchioles.