Carbonic anhydrase IX in tumor tissue and sera of patients with primary cervical cancer

BACKGROUND: Carbonic anhydrase IX (CAIX) is a membranous expressed metalloenzyme involved in pH homeostasis and cell adhesion. The protein is overexpressed in a variety of tumors and potentially associated with negative outcome. This study was designed to investigate the prognostic role of CAIX in serum and tumor tissue of patients with primary cervical cancer. METHODS: Tumor samples of 221 consecutive patients with primary cervical cancer who underwent surgery between 1993 and 2008 were analyzed for CAIX expression by immunohistochemistry. Additionally, preoperative serum CAIX concentrations were determined by ELISA in a subset of patients. Correlation with intratumoral CAIX expression as well as clinicopathological factors and outcome was analyzed. RESULTS: CAIX expression was observed in 81.9% of the tumor specimens; 62.0% showed a moderate or strong staining intensity. Moderate/strong expression was associated with squamous histology (p = 0.024), advanced tumor stage (p = 0.001), greater invasion depth (p = 0.025), undifferentiated tumor grade (p < 0.001) and high preoperative SCC-Ag values (p = 0.042). Furthermore patients with moderate/strong intratumoral CAIX expression had a higher number of metastatic lymph nodes compared to those with none/weak intratumoral expression levels (p = 0.047) and there was a non-significant association between high intratumoral CAIX expression and shorter survival (p = 0.118). Preoperative serum concentrations of CAIX ranged between 23 and 499 pg/mL and did not correlate with intratumoral expression or other clinicopathological variables. CONCLUSION: CAIX is associated with advanced tumor stages and lymph node metastases in cervical cancer, potentially representing a new target in this disease. In contrast to other epithelial cancers we could not observe a correlation between serum CAIX and its intratumoral expression.