**4. Prophylaxis of vein thrombotic events in cancer patients**

Venous thromboembolism in cancer patients is accompanied with poor prognosis due to complications such as pulmonary embolism or reflecting the advanced stages of cancer as the more important factor. Cancer patients are prone to failure of anticoagulation therapy. Receiving anticoagulant agents can lead to major bleeding two to six times. In contrast, venous thromboembolism (VTE) recurrences occur two to three times in these patients. Thus, primary prevention seems to be more effective way to reduce morbidity and mortality related with thrombotic events in patients with malignancy [17]. However, about 75% of patients do not receive appropriate prophylaxis treatment [18].
