Status of targeted therapies in the adjuvant treatment of colon cancer

Colon cancer is the 4^th most common malignancy with 80% of patients diagnosed with early stage disease that is potentially curable with surgery and the addition of adjuvant chemotherapy in select Stage II and all Stage III patients. Adjuvant chemotherapy with 5-flurouracil based regimens has been shown to have overall survival benefit in Stage III disease with some benefit shown in certain sub-populations in Stage II disease. In recent years, targeted therapies directed against vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EFGR) have shown improved survival in metastatic colon cancer. However, trials of these agents in the adjuvant setting showed no benefit. Reasons for failure of these agents in trials thus far include differences in the molecular biology of macrometastatic versus micrometastatic disease and the lack of biologic predictive markers to target the appropriate patient populations for these agents.