Epidemiology of thrombosis in cancer

We have utilized epidemiological data to address three questions in patient s with cancer and venous thromboembolism (VTE): (1) What is the risk for oc cult cancer in patients with idiopathic versus secondary VTE? (2) What is t he risk for thrombosis in patients with cancer (vs. noncancer patients)? (3 ) What is the risk of recurrent VTE in cancer patients with an initial epis ode of VTE compared to noncancer patients? The risk for a new cancer diagno sis within 6-12 months of the diagnosis of idiopathic VTE (including pulmon ary 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 studie s are in the range of 4- to 7-fold increased risk. In surgical patients wit h known cancer the odds ratio for an episode of postoperative VTE is approx imately 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 ini tial episode in cancer patients treated with heparin and warfarin (Coumadin (R)) compared to noncancer patients. Therefore, patients with idiopathic V TE are at increased risk for occult cancer and cancer patients are at incre ased risk for VTE. Appropriate studies are underway to determine the best s trategies for anticoagulant management of these patients. Copyright (C) 200 1 S. Karger AG, Basel.