Tumour markers in metastatic colorectal cancer: clinical implications for treatment with targeted therapy

Targeted therapy with bevacuzimab, cetuximab and panitumumab has expanded the treatment options in metastatic colorectal cancer. Predictive tumour markers for treatment with targeted therapy that have been suggested are Epithelial Growth Factor Receptor (EGFR) and Vascular Endothelial Growth Factor Receptor (VEGFR) expression, KRAS mutation and BRAF mutation status, loss of PTEN and PIK3CA mutation status. Of these, only KRAS has made it into clinical practice. KRAS mutation is a negative predictor for response to cetuximab EGFR inhibitors. No predictive tumour marker for bevacizumab has been identified. In this review, the current evidence on KRAS, BRAF, PTEN, PIK3CA, EGFR and VEGFR expression as predictive tumour markers for targeted therapy is reviewed. (BELG J MED ONCOL 2012;6:52–57)