title: [Significance of detection of serum carbonic anhydrase IX in the diagnosis of lung cancer].
abstract: 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.
authors.affiliation: Department of Medical Oncology, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Fangyuan
authors.initials: F
authors.lastname: Cheng
authors.affiliation: Department of Medical Oncology, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Xiao'e
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Medical Oncology, Tianjin Medical University General Hospital, Tianjin 300052, China;Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Diansheng
authors.initials: D
authors.lastname: Zhong
authors.affiliation: Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Medical Oncology, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Medical Oncology, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D002256:Carbonic Anhydrases / Q000097:blood*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011379:Prognosis
chemical_list: D014408:Biomarkers, Tumor; D002256:Carbonic Anhydrases