FOLFIRI + Bevacizumab With or Without Dalteparin in First Line Treatment of Advanced Colorectal Cancer

This study is for people with colorectal cancer, who have tumors that cannot be completely removed by surgery. Blood clots are a problem in patients with cancer. Blood clots are also a problem in patients receiving cancer drugs. Studies have shown that up to 17% of patients receiving cancer drugs experienced blood-clotting problems. One purpose of this study is to find if the drug combination of irinotecan, 5-fluorouracil (5-FU), bevacizumab and leucovorin (LV) affect blood-clotting factors. A second purpose of this study is to find out what effects the drug dalteparin has on clotting factors in the blood in patients receiving the drug combination of irinotecan, 5-FU, bevacizumab and LV. It is hoped that adding dalteparin to chemotherapy may benefit patients with colorectal cancer by preventing blood clots