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Hypoxia-Associated Marker CA IX Does Not Predict the Response of Locally Advanced Rectal Cancers to Neoadjuvant
Arnulf Mayer1, Peter Vaupel2, Katja Oberholzer3
1Department of Radiooncology and Radiotherapy, University Medical Center, Langenbeckstrasse 1, 55131, Mainz, Germany. arnmayer@uni-mainz.de.
Abstract:
Hypoxia-associated proteome changes have been shown to be associated with resistance to chemo- and radiotherapy. Our study evaluated the role of the hypoxia-inducible (HIF)-1 target gene carbonic anhydrase (CA) IX in the prediction of the response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer (stages II and III). A total of 29 pretreatment biopsy specimens were stained for CA IX by immunohistochemistry, converted to digital images and evaluated in a quantitative fashion using image analysis software. Contrary to our expectations, a trend towards a correlation between better tumor regression (>50%) and higher expression of CA IX (p=0.056) was found. CA IX was also present more frequently in pathological tumor stage T1 (pT1) tumors (p=0.048). Conversely, no association with lymph node metastasis was identified. In conclusion, as a single marker, CA IX expression is not able to identify a hypoxia-related treatment resistant phenotype in rectal cancer.
