Serum carbonic anhydrase 9 level is associated with postoperative recurrence of conventional renal cell cancer

Purpose: We explored the clinical usefulness of serum carbonic anhydrase 9 as a potential biomarker for conventional renal cell cancer. Materials and Methods: This study included 91 patients with conventionat renal cell cancer and 32 healthy individuals. Enzyme linked immunosorbent assay was used to measure the carbonic anhydrase 9 level. A followup (median 38 months) was performed to track early recurrence after surgery for patients with localized disease. Recurrence-free survival curves were calculated by the Kaplan-Meier method and compared using the log rank test. Results: The mean serum carbonic anhydrase 9 level in patients with metastatic conventional renal cell cancer (216.68 +/- 67.02 pg/ml) or localized conventional renal cell cancer (91.65 +/- 13.29 pg/ml) was significantly higher than in healthy individuals (14.59 +/- 6.22 pg/ml, p <0.001 and p = 0.001, respectively). The mean serum carbonic anhydrase 9 level in patients with metastatic conventional renal cell cancer was significantly higher than in those with localized disease (p = 0.004). Of patients with localized disease those with recurrence had a significantly higher serum carbonic anhydrase 9 than those without recurrence (P = 0.001). On univariate analysis serum carbonic anhydrase 9, tumor stage, tumor grade and tumor size were associated with recurrence. The recurrence-free survival curve indicates that patients with a high serum carbonic anhydrase 9 level had a significantly higher recurrence rate than those with a low serum carbonic anhydrase 9 (p = 0.001). Conclusions: Our data suggest that serum carbonic anhydrase 9 is increased as the tumor progression occurs. A high carbonic anhydrase 9 level is associated with postoperative recurrence.