 VTE is an increasingly frequent complication of cancer and anti-cancer therapies. It is associated with increased mortality and other significant adverse consequences. Risk factors for VTE in the cancer population have been identified, and multiple studies have also shown that VTE can be prevented in high-risk populations with the use of thromboprophylaxis. This study evaluated the safety and efficacy of prophylaxis in a high-risk subgroup of cancer patients identified by a validated risk model developed by us previously called the Khorana Score. Correlative studies evaluated the value of tissue factor as a predictive biomarker of VTE. The purpose of this study was to conduct a prospective, randomized clinical trial comparing the safety and efficacy of prophylaxis with dalteparin to no treatment in reducing VTE in high-risk ambulatory cancer patients initiating chemotherapy and to establish the value of TF as a predictive marker for VTE in ambulatory cancer patients receiving chemotherapy. 