**5.2 Unfractionated heparin**

It is an anticoagulant which activate antithrombin to inhibit clotting enzymes, especially thrombin and factor Xa. Research showed that unfractionated heparin is effective to prevent thromboembolism events in cancer patients. Although, the use of low-molecular-weight heparin (LMWH) is associated with higher reduction in thrombotic events compared to unfractionated heparin in patients with malignancy, especially solid tumor due to increasing of inflammatory component on solid tumor rather than others [27, 29].
