 - A risk score for VTE 3 assign score of 2 for very high risk sites of cancer stomach, pancreas, score of 1 for high risk site lung, lymphoma, gynecologic, bladder, testicular and score of 0 for all other sites, hemoglobin 10 gdL or planned use of erythropoiesis stimulating agents, platelet count 350,000mm3, total leukocyte count 11,000mm3 or body mass index 35 kgm2. Any counts meeting criteria drawn within 2 weeks prior to enrollment are considered acceptable. 