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.
背景与目的 碳酸酐酶IX（carbonic anhydrase IX, CAIX）在肺癌等多种恶性肿瘤组织中广泛表达，前期研究证明，肺癌患者血清可溶性CAIX（soluble form of carbonic anhydrase IX, s-CAIX）含量明显高于健康者。本研究检测肺癌恶性胸腔积液中s-CAIX含量和沉淀物中CAIX表达情况，探讨其对肺癌的诊断价值。方法 运用EILSA检测29例肺癌恶性胸腔积液和27例结核性胸腔积液中s-CAIX含量。运用免疫组化法检测21例肺癌恶性胸腔积液沉淀物和6例良性胸腔积液沉淀物中CAIX表达。绘制胸腔积液s-CAIX诊断肺癌恶性胸腔积液的ROC曲线。结果 肺癌恶性胸腔积液较结核性胸腔积液中s-CAIX含量明显增高（P<0.05）。胸腔积液s-CAIX诊断肺癌恶性胸腔积液的受试者工作特征（receiver operating characteristic, ROC）曲线下面积为0.761，当胸腔积液中s-CAIX阈值为109.135 pg/mL时，敏感度和特异度分别为92.3%和58.3%。良性胸腔积液沉淀物组中CAIX表达均阴性，肺癌恶性胸腔积液沉淀物中CAIX表达阳性率66.67%。结论 胸腔积液及其沉淀物CAIX检测有助于肺癌恶性胸腔积液诊断，且具有较高的敏感性和特异性。.