Prothrombotic factors in cancer include the ability of tumor cells to produce and secrete procoagulant (tissue factor, cancer procoagulant, and factor V receptor)/fibrinolytic substances (plasminogen activator and plasminogen activator inhibitor-1, 2) and inflammatory cytokines (IL-1b, TNF-a, and VEGF) and the physical interaction between tumor cell and blood (monocytes, platelets, and neutrophils) or vascular cells. This evidence concerns the gene IL1B and cancer.