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

Inclusion Criteria: * Histologically-confirmed metastatic colorectal cancer (primary tumor or metastasis) * Confirmation of KRAS wildtype status * Confirmation of EGFR-Expression in the tumor * Stadium IV * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 * Qualified for an application of FOLFIRI + Cetuximab treatment * Signed patient informed consent form * Of either gender and aged 18 years or more * Estimated lifespan more than 3 months * Measurable disease according to RECIST 1.1 guidelines. The evaluation has to be max. 4 weeks * Effective and adequate contraceptive precautions of man or woman in a childbearing potential age (double barrier method) * Leucocytes ≥ 3,0 x 10\^9/L with neutrophils ≥ 1,5 x 10\^9/L, thrombocytes ≥ 100 x 10\^9/L, haemoglobin ≥ 5,6 mmol/L * Serum bilirubin ≤ 1,5 x ULN (upper limit of normal) * ALAT and ASAT ≤ 2,5 x ULN; if metastasis in liver, than ALAT and ASAT ≤ 5 x ULN * Serum creatinin ≤ 1,5 x ULN * If applicable a prior operation has to be min. 4 weeks ago, biopsy more than 1 week until initiation of treatment. Wounds of operations had to be completely cured * No toxicity of prior treatments Exclusion Criteria: * KRAS-gene mutation * Confirmation of non-EGFR-Expression * Prior treatment with an EGRF-receptor inhibitor * Prior chemotherapy of the mCRC, except (neo-)adjuvant therapy, which had to be ended min. 6 months before recruitment * Experimental treatment medication within 30 days before recruitment * Known hypersensitivity against components of the chemotherapy, cetuximab, doxycycline, Reconval K1 or Dermatop * Rosacea * Other chronic dermal diseases with development of papula or pustule * Known lung fibrosis or interstitial pneumonitis or interstitial lung diseases * keratitis, ulcerative keratitis or severe form of dry eye * Pregnancy or breast feeding * Brain metastasis * Clinical relevant coronary heart disease, myocardial infarction within the last 12 months or high risk of uncontrollable arrhythmia * Acute or subacute ileus or chronic colon-inflammation or chronic diarrhea * Symptomatic peritoneal carcinomatosis * Serious, non-healing wounds, ulcera or bone fractures * Uncontrollable arterial hypertension * Therapeutic anticoagulation (e.g. therapy with marcumar) * Known dihydropyrimidine dehydrogenase deficiency * Gilbert-Meulengracht-syndrome * Other malignant tumours less than five years old. Exceptions include basocellular carcinoma or an in situ cancer of the cervix uteri if they are curative treated as well as an untreated, locally confined, asymptotic "low risk" (indolent) prostata carcinoma (Stage T ≤ T1-2a, PSA \< 15 ng/ml, Gleason-Score ≤ 6 ). * Known abuse of narcotic drugs or alcohol * Any kind of disorder that compromises the ability of the subject to give written informed consent and/or comply with the study procedures * Any significant concomitant disease that excludes the participation to the study * Missing or limited juristic contractual capability