ABSTRACT
The association of venous thromboembolism (VTE) with cancer has been known for many years (1). Recent estimates suggest that the annual incidence of VTE in the cancer population is 0.5%, compared with 0.1% in the general population (2). The actual frequency is probably even greater, given recent studies showing a rapid increase in incidence starting
in the late 1990s (3,4). Cancer patients comprise a heterogeneous group including patients on active therapy, patients undergoing surgery, hospitalized patients, cancer survivors, and patients with terminal illness. The risk of VTE in some of these subgroups is substantially higher than that estimated for the general cancer population. Table 1 lists the established and possible risk factors for cancer-associated VTE. All of these risk factors must be taken into account when assessing risk for individual patients. Further, it is imperative to note that risk factor assessment is a dynamic process and can change rapidly over time based on multiple cancer-and treatment-related factors. This is illustrated in Figure 1, which describes changes in relative risk for a representative cancer patient over the natural course of the disease.
