Bevacizumab (AvastinTM), a monoclonal antibody to VEGF-A, was approved by United States Food and Drug Administration (FDA) in 2004 and has proven clinical benefits in treatment of metastatic colorectal cancer when the drug was added to standard chemotherapy and also has positive results in metastatic kidney cancer and advanced lung cancer. This evidence concerns the gene VEGFA and metastatic colorectal cancer.