摘要：Carcinoembryonic antigen (CEA) is not only used to aid the diagnosis of lung cancer, but also help monitor recurrence and determine the prognosis of lung cancer as well as evaluate the therapeutic efficacy for lung cancer. However, studies have also shown that CEA is present at low levels in the serum of patients with benign lung diseases (BLD), which will interfere with the accurate judgment of the disease. Due to difference in sample size, detection methods, cutoff values and sources of BLD, the positive rate of CEA in BLD is different with different literature. Therefore, it is necessary to define CEA levels in patients of different BLD in a large sample study. 4796 patients with BLD were included in this study. The results showed that the CEA levels of 3.1% (149/4796) patients with BLD were elevated, with three cases exceeds 20 ng/mL (0.06%, 3/4796). The results from the literature showed that BLD had a mean positive rate of 5.99% (53/885) and only two cases had CEA above 20 ng/mL. The CEA elevations mainly distributed in chronic obstructive pulmonary disease (COPD), pneumonitis and interstitial lung disease and significantly correlated with age of patients (OR 2.69, 95% CI 1.94–3.73, p < 0.001). Pulmonary tuberculosis (7/1311, 0.53%) had the lowest positive rate of CEA elevations while pulmonary alveolar proteinosis (6/27, 22.22%) had the highest positive rate. The majority of patients with abnormally elevated CEA levels had multiple underlying diseases, mainly diseases of the circulatory system (42.28% [63/149
