[Systemic treatment of advanced colorectal cancer].

The introduction of modern chemotherapeutic drugs and targeted therapies has substantially changed the treatment of advanced colorectal cancer (aCRC). Thus, median survival of stage IV patients was increased from 6 months under best supportive care to over 2 years if all drugs are administered. Also, new combination therapies may cause irresectable liver metastases to shrink to such an extent that they may be resected (downsizing). Patients who were formerly treated with palliative intent may now be cured. However, not all patients benefit from the new compounds. Very recently, new genetic characteristics were identified as potential molecular biomarkers that may predict response to anti-EGFR therapy, a specific targeted therapy; the marker detected is the mutational status of the oncogene k-ras. Only patients with wild-type k-ras-expressing tumors respond to anti-EGFR antibodies. The integration of biomarker analysis into the clinical routine represents an important step toward customized treatment of cancer patients.