Radioimmunoassay for detecting serum carcinoembryonic antigen in benign and malignant lung diseases

Objective: To make a retrospective analysis of radioimmunoassay for detecting serum carcinoembryonic antigen (CEA) in the diagnosis of benign and malignant lung diseases. Methods: Iodine [¹²⁵I] radioimmunoassay was used to detect serum CEA in 331 patients with lung cancer and 98 cases of tuberculosis (TB). Results: The patients with lung cancer had a positive rate of 29.61% of CEA, which was significantly higher than that of TB patients (P<0.01). Serum CEA for diagnosis of lung cancer had a sensitivity of 29.61%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 29.61%. Serum CEA-positive rate of adenocarcinoma was the highest 54.55%, and so was the CEA concentration. These two parameters differed significantly (P<0.01) when compared with those of small cell lung cancer and squamous cell carcinoma. CEA-positive rate had no significant difference between early or medium stage and advanced stage of lung cancer, but the concentration of CEA was increased significantly with tumor stage (P<0.01), the later the higher the concentration. Conclusion: Radioimmunoassay has a very high specificity in detecting the level of serum CEA. Therefore, it may be important for the diagnosis and assessment of lung cancer.