[Value of Detection of CAIX in the Pleural Effusion and Its Sediment in the Diagnosis of Lung Cancer].

ABSTRACT

BACKGROUND AND OBJECTIVE: Carbonic anhydrase IX (CAIX) is widely expressed in a variety of malignant tumors, including-lung cancer. Our previous study has shown that the serum level of soluble form of carbonic anhydrase IX (s-CAIX) was significantly higher in patients with lung cancer than that in the healthy group. The aim of this study is to detect the s-CAIX level in the pleural effusion and its sediment, and to evaluate the significance of CAIX detection in the diagnosis of lung cancer. METHODS: The s-CAIX level in pleural effusion of 29 lung cancer patients and 27 patients with tuberculosis was detected by ELISA. The expression of CAIX in the pleural effusion sediment of 21 lung cancer patients with malignant pleural effusion and 6 patients with benign pleural effusion was examined by immunohistochemistry. With pathological diagnosis as the gold standard, receiver operating characteristic (ROC) curve of pleural effusion s-CAIX was established for the diagnosis of lung cancer with malignant pleural effusion. RESULTS: The s-CAIX level in the malignant pleural effusion was significantly higher than that in the tuberculosis group (P<0.05). The AUC of pleural effusion s-CAIX level was 0.761. At a threshold level of 109.135 pg/mL, sensitivity and specificity were 92.3% and 58.3%, respectively. The CAIX expression in all samples of the benign pleural effusion sediment was negative. The positive rate of CAIX expression in malignant pleural effusion sediment was 66.67%. CONCLUSIONS: Detection of CAIX in the pleural effusion and its sediment exhibits high sensitivity and specificity, and is helpful in diagnosis of lung cancer with malignant pleural effusion.