<qa>  What is the average age of ECOG PS?Histologically proven diagnosis of colorectal cancer Initially unresectable metastatic colorectal cancer not previously treated with chemotherapy for metastatic disease At least one measurable lesion according to RECIST1.1 criteria Availability of a tumoral sample Male or female of 18-75 years of age ECOG PS or 2 if aged 71 years, ECOG PS 0 if aged 71-75 years Life expectancy of at least 12 weeks Previous adjuvant chemotherapy allowed only if with fluoropyrimidine monotherapy and more than 6 months elapsed between the end of adjuvant and first relapse Neutrophils 1.5 x 109L, Platelets 100 x 109L, Hgb 9 gdl Total bilirubin 1.5 time the upper-normal limits UNL of the normal values and ASAT SGOT andor ALAT SGPT 2.5 x UNL or 5 x UNL in case of liver metastases alkaline phosphatase 2.5 x UNL or 5 x UNL in case of liver metastases Creatinine clearance 50 mLmin or serum creatinine 1.5 x UNL Urine dipstick of proteinuria 2. Patients discovered to have 2 proteinuria on dipstick urinalysis at baseline, should undergo a 24-hour urine collection and must demonstrate 1 g of protein24 hr Will and ability to comply with the protocol Written informed consent to study procedures and to molecular analyses - 