Background: Carbonic anhydrase IX (CAIX) is a transmembrane protein involved in the metabolism of tumor cells. CAIX is expressed in only a few normal tissues but is overexpressed in various tumor types. The aim of this study is to detect the serum CAIX level of patients with lung cancer, evaluate the significance of CAIX detection in the diagnosis of lung cancer, and analyze the serum CAIX level among different pathological types and TNM stages of lung cancer.
Methods: Forty-seven patients with lung cancer and 31 healthy subjects were selected to participate in this study. Serum CAIX level was examined through enzyme-linked immunosorbent assay (ELISA). The subjects were grouped according to histological type and TNM staging, and serum CAIX level was compared among the groups. With pathological diagnosis as the gold standard, receiver operating characteristic curve of the serum CAIX level was established for the diagnosis of lung cancer.
Results: The CAIX serum level was significantly higher in patients with lung cancer than that in the healthy group (P<0.001). The serum CAIX level in patients with squamous cell carcinoma and small cell carcinoma was also significantly higher than that in patients with adenocarcinoma. No statistically significant differences were observed in the serum CAIX level between I+II and III+IV staging. The AUC of serum CAIX level was 0.961. At a threshold level of 115.115 pg/mL, sensitivity and specificity were 95.7% and 90.3%, respectively.
Conclusions: Detection of the serum CAIX level through ELISA exhibits high sensitivity and specificity and is important for the diagnosis of lung cancer.
背景与目的 碳酸酐酶IX（carbonic anhydrase IX, CAIX）是一种跨膜蛋白，参与肿瘤细胞的代谢过程。其在少数正常组织中低表达，但在多种恶性肿瘤组织中广泛表达。检测CAIX在肺癌患者血清中的含量，探讨其对肺癌的诊断价值，分析不同病理类型及TNM分期肺癌患者血清CAIX含量是否存在差异。方法 选取47例肺癌患者和31例健康体检者为研究对象，用酶联免疫吸附测定（enzyme linked immunosorbent assay, ELISA）法检测其血清CAIX含量，根据病理类型及TNM分期分组，比较各组血清CAIX差异；绘制血清CAIX诊断肺癌的受试者工作特征曲线（receiver operating characteristic curve, ROC）。结果 肺癌组较健康对照组血清CAIX含量明显增高（P<0.001）；鳞癌和小细胞癌患者血清CAIX含量明显高于腺癌患者。I期+II期与III期+IV期的肺癌患者血清CAIX含量比较，未发现两者间的差异有统计学意义；血清CAIX诊断肺癌的ROC曲线下面积为0.961，当血清中CAIX阈值为115.115 pg/mL时，敏感度和特异度分别为95.7%和90.3%。结论 用ELISA法检测患者血清CAIX有助于肺癌诊断，且具有较高的敏感性和特异性。