Stromal expression of carbonic anhydrase IX in esophageal cancer.

Purpose: 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.

Methods/patients: 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.

Results: 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).

Conclusion: 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.