Stromal expression of carbonic anhydrase IX in esophageal cancer

Carbonic anhydrase IX (CA IX), a transmembrane glycoprotein, is known as an endogenous marker for hypoxia. Overexpressed in cancer-associated fibroblasts, CA IX has been reported to be associated with a poor outcome for a number of malignant tumors. Aim of this study was to investigate the role of CA IX in the tumor surrounding stroma of esophageal cancer. Stromal expression of CA IX in 361 formalin-fixed, paraffin-embedded specimens of invasive esophageal cancers, 206 adenocarcinoma (AC) and 155 squamous cell carcinoma (SCC), was investigated. In 42 cases (11.6 %), CA IX expression in the tumor surrounding stroma (AC 23 and SCC 19) was observed. Expression of CA IX correlated with the factors tumor stage (p < 0.001) and lymph node status (p = 0.008). Patients with CA IX expressed in the tumor surrounding stroma had a significant shorter disease-free survival (p = 0.007) and overall survival (p = 0.013). In esophageal cancer, CA IX-expressing tumor stroma is associated with shorter survival. Inhibition of the tyrosine kinase CA IX might represent a new onset for therapies against esophageal cancer.