Thrombin Generation and Cancer: Contributors and Consequences

Abstract

The high occurrence of cancer-associated thrombosis is associated with elevated thrombin generation. Tumour cells increase the potential for thrombin generation both directly, through the expression and release of procoagulant factors, and indirectly, through signals that activate other cell types (including platelets, leukocytes and erythrocytes). Furthermore, cancer treatments can worsen these effects. Coagulation factors, including tissue factor, and inhibitors of coagulation are altered and extracellular vesicles (EVs), which can promote and support thrombin generation, are released by tumour and other cells. Some phosphatidylserine-expressing platelet subsets and platelet-derived EVs provide the surface required for the assembly of coagulation factors essential for thrombin generation in vivo. This review will explore the causes of increased thrombin production in cancer, and the availability and utility of tests and biomarkers. Increased thrombin production not only increases blood coagulation, but also promotes tumour growth and metastasis and as a consequence, thrombin and its contributors present opportunities for treatment of cancer-associated thrombosis and cancer itself.

Keywords: cancer; extracellular vesicles; neutrophil extracellular traps; platelets; procoagulant platelets; thrombin generation; thrombosis.

Figure 1

The high occurrence of cancer-associated thrombosis is associated with elevated thrombin generation. Tumour cells increase the potential for thrombin generation both directly, through the expression and release of procoagulant factors, and indirectly, through signals that activate other cell types and components including platelets, leukocytes, erythrocytes, extracellular vesicles (EVs) and neutrophil extracellular traps (NETs). Chemotherapy and the prevailing inflammatory milieu caused by the presence of cancer can stimulate tumour cells and other host cellular components to be procoagulant. Many of these factors potentiate thrombin generation through the expression of tissue factor bearing surfaces that mediates the assembly of coagulation factors essential for the formation of thrombin in vivo. Elevated thrombin production not only increases the risk of thrombosis, but also promotes tumour growth and metastasis and as a consequence, thrombin and its contributors present opportunities for treatment of cancer-associated thrombosis and the underlying cancer.