Thromboembolic complications of malignancy. Part 1: Risks.

Thromboembolism affects many patients with solid tumors and clonal hematologic malignancies. Pathogenetic mechanisms include inflammatory- and tissue factor-mediated coagulation, natural anticoagulant deficiencies, fibrinolytic alterations, hyperviscosity, and activation of platelets, endothelial cells, and leukocytes. High rates of venous thromboembolism (VTE) occur with advanced pancreatic, breast, ovarian, germ cell, lung, prostate, and central nervous system cancers. Hodgkin disease, non-Hodgkin's lymphoma, myeloma, paroxysmal nocturnal hemoglobinuria, and certain leukemias also predispose to venous thromboembolism. Arterial and venous events occur with polycythemia vera and essential thrombocythemia. Central venous catheters and prothrombotic antitumor regimens augment the risk in some patients. Part 1 of this two-part article addresses pathophysiology, clinical presentations, and risk of malignancy-associated thrombosis. Part 2, which will appear in next month's issue, covers prophylaxis and treatment of these thromboembolic complications.