title: Carbonic anhydrase IX (CAIX) is not an independent predictor of outcome in patients with clear cell renal cell carcinoma (ccRCC) after long-term follow-up.
abstract: OBJECTIVE
  To evaluate carbonic anhydrase IX (CAIX) expression as an independent prognostic marker for clear cell renal cell carcinoma (ccRCC). With recent smaller studies showing conflicting results, we aimed to update our initial analysis in 2007 with an additional 5-year follow-up.
  
  
  METHODS
  We provided long-term follow-up of the same cohort used in our 2007 study (730 patients with unilateral, sporadic ccRCC treated surgically between 1990 and 1999). Associations of CAIX expression with RCC death and distant metastases were evaluated using Cox proportional hazards regression models.
  
  
  RESULTS
  CAIX was expressed in 708 (97.0%) of the specimens; 163 tumours (22.3%) had low (≤85%) expression and 567 (77.7%) high (>85%) expression. There were 483 deaths and 265 RCC-specific deaths. The median follow-up for the 247 patients still under observation was 13.8 years. Univariately, low CAIX expression was associated with an increased risk of RCC death vs high expression (hazard ratio 1.62; P < 0.001). Low CAIX expression was not statistically significantly associated with RCC death or distant metastases after adjusting for nuclear grade or coagulative tumour necrosis.
  
  
  CONCLUSIONS
  After additional long-term follow-up of our large cohort, our results continue to suggest that CAIX is not an independent prognostic marker for ccRCC.
authors.affiliation: Department of Internal Medicine, Mayo Clinic and Mayo Medical School, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Ben Y
authors.initials: BY
authors.lastname: Zhang
authors.forename: R Houston
authors.initials: RH
authors.lastname: Thompson
authors.forename: Christine M
authors.initials: CM
authors.lastname: Lohse
authors.forename: Roxana S
authors.initials: RS
authors.lastname: Dronca
authors.forename: John C
authors.initials: JC
authors.lastname: Cheville
authors.forename: Eugene D
authors.initials: ED
authors.lastname: Kwon
authors.forename: Bradley C
authors.initials: BC
authors.lastname: Leibovich
mesh_terms: D000368:Aged; D000951:Antigens, Neoplasm / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002292:Carcinoma, Renal Cell / Q000378:metabolism* / Q000401:mortality; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000378:metabolism* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D009336:Necrosis / Q000378:metabolism; D009392:Nephrectomy; D011237:Predictive Value of Tests; D011379:Prognosis; D011795:Surveys and Questionnaires; D016019:Survival Analysis; D013997:Time Factors
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases