Cancer-Associated Thrombosis: A Two-Way Street

Pathological activation of the coagulation system occurs with virtually all forms of cancer, particularly epithelial malignancies. Accordingly, thrombosis is one of the most common comorbidities associated with cancer. Indeed, cancer-associated thromboembolism is the second leading cause of death for cancer patients, second only to the cancer itself. The identification of specific molecular mechanisms whereby tumor cells activate the coagulation system and drive thrombosis has been an active area of investigation for several decades. Studies in animal models and human trials have revealed that there is a bidirectional relationship between coagulation factor activity and cancer, whereby the pathological hemostatic system activation associated with cancer not only promotes thromboembolism but also drives progression of the malignancy. Numerous studies indicate that factors up and down the clotting cascade can contribute to various stages of cancer, including tumorigenesis, primary tumor growth, and metastasis. Although there are some mechanistic points of commonality, there are also clearly context-dependent contributions of coagulation components to cancer progression dependent on the type of cancer and stage of disease. It is also notable that in some instances, coagulation factors appear to contribute to cancer progression independently of their traditional roles in hemostasis and thrombosis. Here, the authors review the current state of the field with regard to hemostatic factor-driven cancer pathogenesis.