Epidemiology and management of venous thromboembolism in patients with cancer.

Cancer and its treatments are well-recognized risk factors for venous thromboembolism (VTE). Although the incidence of VTE in cancer patients is not well documented, there is evidence that the absolute risk depends on the tumor type, the stage or extent of the cancer, and treatment with antineoplastic agents. The most common cancer types seen in patients with thrombosis are breast, colorectal and lung, reflecting the prevalence of these malignancies in the general population. When the underlying prevalence is taken into account, cancers of the pancreas, ovary and brain are the most strongly associated with thrombotic complications. Although idiopathic thrombosis can be the first manifestation of an occult malignancy, extensive screening for cancer in these patients has not been shown to improve survival and is not warranted. Prophylaxis in patients undergoing major surgery for cancer with either unfractionated or low-molecular-weight heparin (LMWH) is strongly recommended, but prophylaxis in ambulatory medical oncology patients is not routinely indicated. Anticoagulant therapy remains the mainstay treatment of VTE in cancer patients and recent evidence shows that LMWH is effective and well tolerated for both initial therapy and secondary prophylaxis. Despite treatment, cancer patients with thrombosis have a poor prognosis. This is likely due to premature deaths from recurrent VTE and to the aggressive nature of the underlying cancer. Whether LMWH is capable of modifying tumour biology remains unanswered. Further research is needed to address the many clinical questions in the management of thrombosis in patients with cancer.