Treatment options for patients with colorectal cancer (CRC) have increased in the last years. However, there are no validated prospective molecular markers in CRC to select which agents are better to treat any individual case. The conventional first-line treatment in CRC patients in clinical studies get a proportion of patients free of progression at 12 months ranging from 35-40% with a median of 9 months of free disease progression.

The aim of this study is to demonstrate that the identification of therapeutic targets in real time and their prospectively use to customize the treatment get a proportion of colorectal metastatic patients patients free of progression disease at 12 months of 50%.

Inclusion Criteria:

• Colorectal adenocarcinoma stage IV patients.
• ECOG= 0-1
• Age > 18 years.
• Fit to receive chemotherapy treatment
• Availability of tumor tissue or possibility of a tumor biopsy to determine therapeutic targets.
• Adequate renal (Cr < 1,5 mg/d), liver (bilirubin≤1,5 mg/dl, AST and ALT ≤ 3.0 x the upper limit of normal) and normal bone marrow function ( absolute neutrophil count ≥ 1500/µl, hemoglobin ≥ 9.0g/dl and a platelet count of ≥ 100.000/µl)

Exclusion Criteria:

• Contraindication for the administration of any of the drugs used in the study including capecitabine, irinotecan, oxaliplatin, cetuximab or bevacizumab.
• Previous Chemotherapy treatment