Epidemiology of thrombosis in cancer

We have utilized epidemiological data to address three questions in patients with cancer and venous thromboembolism (VTE): (1) What is the risk for occult cancer in patients with idiopathic versus secondary VTE? (2) What is the risk for thrombosis in patients with cancer (vs. noncancer patients)? (3) What is the risk of recurrent VTE in cancer patients with an initial episode of VTE compared to noncancer patients? The risk for a new cancer diagnosis within 6-12 months of the diagnosis of idiopathic VTE (including pulmonary embolism) is well supported by retrospective analyses of large numbers of unselected patients, population-based retrospective cohort analyses from large registries and prospective studies. The odds ratios for these studies are in the range of 4- to 7-fold increased risk. In surgical patients with known cancer the odds ratio for an episode of postoperative VTE is approximately 2, when compared to a control group of noncancer patients subjected to the same procedures. A similar odds ratio of approximately 2 exists for the relative risk for recurrence of VTE in the first 3 months after an initial episode in cancer patients treated with heparin and warfarin (Coumadin (R)) compared to noncancer patients. Therefore, patients with idiopathic VTE are at increased risk for occult cancer and cancer patients are at increased risk for VTE. Appropriate studies are underway to determine the best strategies for anticoagulant management of these patients. Copyright (C) 2001 S. Karger AG, Basel.