FOLFIRI in Combination With Cetuximab in the First-line Treatment of Metastatic Colorectal Cancer Including a Regular Dermal Prophylaxis to Prevent Acneiforme Follicular Exanthema

The purpose of this interventional study is to assess the progression free survival (one year) of patients with treatment of FOLFIRI and cetuximab, combined with an optional dermal prophylaxis. Further Objectives: 1. Development of acneiforme follicular exanthema \>= grade 2 2. Duration until development of acneiforme follicular exanthema \>= grade 2 3. Development of paronychia 4. Development skin fissure (hand and foot) 5. Objective remission according RECIST 1.1 6. Rate of secondary resections of liver metastasis with a curative approach 7. Assessment of safety and tolerability 8. Overall survival 9. Progression free survival