Using Positron Emission Tomography to Evaluate the Effects of Bevacizumab on Intra-tumoral Pharmacokinetics of 5-fluorouracil in Metastatic Colorectal Cancer

The purpose of this study is to investigate whether bevacizumab helps 5-Fluorouracil (5-FU) be delivered to the tumor more efficiently. Bevacizumab has been shown to inhibit the formation of new blood vessels in tumors and works best in combination with drugs that require blood vessels for transportation. Based on other experiments, bevacizumab may work by improving the transportation of other drugs to the tumor.