This study evaluates the relationship of biomarker expression and efficacy of bevacizumab plus chemotherapy in patients with unresectable/metastatic colorectal cancer. Before the treatment, the investigators detect the VEGF-A,VEGF-C,VEGF-D,VEGFR-1,VEGFR-2,VEGFR-3 expression in tumor tissue by IHC and detect those protein expression level in plasma by ELISA. After at least 6 weeks treatment, the investigators detect again VEGF-A,VEGF-C,VEGF-D expression level in plasma by ELISA. The aim of the study is to identify whether those biomarkers could predict Bevacizumab efficacy.

Inclusion Criteria:

• More than 18-years old,male or female
• Pathologically approved as unresectable/metastatic colorectal cancer
• KPS > 70% or ECOG 0-2
• HGB > 80 g/L, NEUT ≥ 1.5x109 /L, PLT ≥ 80x109 /L; CR < 1.5 x Upper normality，
• TB < 1.5 X Upper normality，AST or ALT < 2.5 x Upper normality.
• Signed consent

Exclusion Criteria:

• Other malignancies simultaneously except in situ cervix or nonmelanoma skin cancer
• Pregnancy or in lactation
• HGB < 80 g/L, NEUT < 1.5x109 /L, PLT < 80x109 /L; CR ≥ 1.5 x Upper normality， TB ≥ 2.5 X Upper normality，AST or ALT ≥2.5 x Upper normality，AKP ≥ 2.5 X Upper normality