Abstract
BACKGROUND: Carbonic anhydrase IX (CAIX) is involved in pH homeostasis, growth and survival of tumor cells. Besides the membranous form of CAIX, a soluble form is detectable in serum (s-CAIX). Overexpression of CAIX in tumors offers the opportunity for therapeutic strategies such as CAIX targeting antibodies. The aim of this study was to examine the relationships of CAIX mRNA expression and s-CAIX levels with clinicopathological parameters and survival of patients with primary breast cancer. METHODS: Tumor tissue of 169 primary breast cancer patients was analyzed for RNA expression by microarray analysis (Affymetrix HG-U133A). Concentration of s-CAIX was determined by ELISA in blood samples of 140 patients. RESULTS: In tumor tissue, CAIX mRNA signal intensities (MAS5 values) ranged from 34 to 2,513. Higher CAIX expression was associated with younger age (