Biomarkers in colorectal cancer: the future is getting closer

Colorectal cancer is the third most common cancer worldwide and the second leading cause of cancerrelated death in the Western world. Approximately 75% of patients with colorectal cancer present with localised disease, whereas metastatic disease accounts for 25% of newly diagnosed patients. Systemic treatment is based on cytotoxic agents and monoclonal antibodies targeting epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF). In the last decade, the optimal use of these agents in patients with metastatic disease has dramatically improved median survival from 6 to 24 months. However, despite all these therapeutic advances, the prognosis of patients with metastatic colorectal cancer remains poor, and, apart from those having surgery of isolated metastases, long-term survival is very low. In the adjuvant setting, 5-fl uorouracil- and oxaliplatinbased chemotherapy has demonstrated a signifi cant improvement in disease-free and overall survival, particularly in patients with resected stage III disease. The quantitative benefi t of adjuvant therapy in patients with stage II colorectal cancer is less important and remains a matter of controversy. However, despite this strategy, almost 40% of patients diagnosed initially with localised disease will develop recurrences. Therefore, there is a need to better identify these patients at risk and to adapt to them what we could consider optimal treatment. Anatomic criteria defi ned by Dukes [1] almost 80 years ago are currently the basis of the tumour/node/metastasis (TNM) staging system upon which most clinical decisions concerning postoperative treatment are based. However, some changes are expected to occur in the