Background and objective: 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.
Methods: 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.
Results: 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; R2 = 0.20 for forced vital capacity and P = 0.006; R2 = 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.
Conclusions: 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.