Drugs used against cancer work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Monoclonal antibodies, such as cetuximab, can block tumor growth in different ways. Giving combination chemotherapy together with cetuximab as first treatment after diagnosis of a metastatic colorectal cancer ('1st-line' treatment) may improve the treatment efficacy. However, it is not yet known whether giving combination chemotherapy together with cetuximab is more effective than combination chemotherapy alone. This open-label trial investigates the effectiveness of cetuximab in combination with a standard and effective chemotherapy (5-Fluorouracil/Folinic acid plus irinotecan) for metastatic colorectal cancer in first-line setting, compared to the same chemotherapy alone on patient expressing the EGF receptor.

Patients expressing this EGF Receptor will be randomly assign in one of the 2 groups to either receive the combination chemotherapy alone or with cetuximab (open-label study) and will then be treated until progression of the disease or unacceptable toxicity occur. Regular efficacy assessments (every 8 weeks) based on imaging will be performed throughout the study together with regular safety assessments (e.g. safety labs). An independent Safety Board of experts will also monitor safety data.

After participant discontinuation from the trial, regular updates on further treatments and survival status will be requested from the investigator.

The entire study (from the first patient entering the study to the last collect of follow-up information) is 4-5 years long.